drm/meson: remove drm bridges at aggregate driver unbind time

In the Linux kernel, the following vulnerability has been resolved:

drm/meson: remove drm bridges at aggregate driver unbind time

drm bridges added by meson_encoder_hdmi_init and meson_encoder_cvbs_init
were not manually removed at module unload time, which caused dangling
references to freed memory to remain linked in the global bridge_list.

When loading the driver modules back in, the same functions would again
call drm_bridge_add, and when traversing the global bridge_list, would
end up peeking into freed memory.

Once again KASAN revealed the problem:

[ +0.000095] =============================================================
[ +0.000008] BUG: KASAN: use-after-free in __list_add_valid+0x9c/0x120
[ +0.000018] Read of size 8 at addr ffff00003da291f0 by task modprobe/2483

[ +0.000018] CPU: 3 PID: 2483 Comm: modprobe Tainted: G C O 5.19.0-rc6-lrmbkasan+ #1
[ +0.000011] Hardware name: Hardkernel ODROID-N2Plus (DT)
[ +0.000008] Call trace:
[ +0.000006] dump_backtrace+0x1ec/0x280
[ +0.000012] show_stack+0x24/0x80
[ +0.000008] dump_stack_lvl+0x98/0xd4
[ +0.000011] print_address_description.constprop.0+0x80/0x520
[ +0.000011] print_report+0x128/0x260
[ +0.000008] kasan_report+0xb8/0xfc
[ +0.000008] __asan_report_load8_noabort+0x3c/0x50
[ +0.000009] __list_add_valid+0x9c/0x120
[ +0.000009] drm_bridge_add+0x6c/0x104 [drm]
[ +0.000165] dw_hdmi_probe+0x1900/0x2360 [dw_hdmi]
[ +0.000022] meson_dw_hdmi_bind+0x520/0x814 [meson_dw_hdmi]
[ +0.000014] component_bind+0x174/0x520
[ +0.000012] component_bind_all+0x1a8/0x38c
[ +0.000010] meson_drv_bind_master+0x5e8/0xb74 [meson_drm]
[ +0.000032] meson_drv_bind+0x20/0x2c [meson_drm]
[ +0.000027] try_to_bring_up_aggregate_device+0x19c/0x390
[ +0.000010] component_master_add_with_match+0x1c8/0x284
[ +0.000009] meson_drv_probe+0x274/0x280 [meson_drm]
[ +0.000026] platform_probe+0xd0/0x220
[ +0.000009] really_probe+0x3ac/0xa80
[ +0.000009] __driver_probe_device+0x1f8/0x400
[ +0.000009] driver_probe_device+0x68/0x1b0
[ +0.000009] __driver_attach+0x20c/0x480
[ +0.000008] bus_for_each_dev+0x114/0x1b0
[ +0.000009] driver_attach+0x48/0x64
[ +0.000008] bus_add_driver+0x390/0x564
[ +0.000009] driver_register+0x1a8/0x3e4
[ +0.000009] __platform_driver_register+0x6c/0x94
[ +0.000008] meson_drm_platform_driver_init+0x3c/0x1000 [meson_drm]
[ +0.000027] do_one_initcall+0xc4/0x2b0
[ +0.000011] do_init_module+0x154/0x570
[ +0.000011] load_module+0x1a78/0x1ea4
[ +0.000008] __do_sys_init_module+0x184/0x1cc
[ +0.000009] __arm64_sys_init_module+0x78/0xb0
[ +0.000009] invoke_syscall+0x74/0x260
[ +0.000009] el0_svc_common.constprop.0+0xcc/0x260
[ +0.000008] do_el0_svc+0x50/0x70
[ +0.000007] el0_svc+0x68/0x1a0
[ +0.000012] el0t_64_sync_handler+0x11c/0x150
[ +0.000008] el0t_64_sync+0x18c/0x190

[ +0.000016] Allocated by task 879:
[ +0.000008] kasan_save_stack+0x2c/0x5c
[ +0.000011] __kasan_kmalloc+0x90/0xd0
[ +0.000007] __kmalloc+0x278/0x4a0
[ +0.000011] mpi_resize+0x13c/0x1d0
[ +0.000011] mpi_powm+0xd24/0x1570
[ +0.000009] rsa_enc+0x1a4/0x30c
[ +0.000009] pkcs1pad_verify+0x3f0/0x580
[ +0.000009] public_key_verify_signature+0x7a8/0xba4
[ +0.000010] public_key_verify_signature_2+0x40/0x60
[ +0.000008] verify_signature+0xb4/0x114
[ +0.000008] pkcs7_validate_trust_one.constprop.0+0x3b8/0x574
[ +0.000009] pkcs7_validate_trust+0xb8/0x15c
[ +0.000008] verify_pkcs7_message_sig+0xec/0x1b0
[ +0.000012] verify_pkcs7_signature+0x78/0xac
[ +0.000007] mod_verify_sig+0x110/0x190
[ +0.000009] module_sig_check+0x114/0x1e0
[ +0.000009] load_module+0xa0/0x1ea4
[ +0.000008] __do_sys_init_module+0x184/0x1cc
[ +0.000008] __arm64_sys_init_module+0x78/0xb0
[ +0.000008] invoke_syscall+0x74/0x260
[ +0.000009] el0_svc_common.constprop.0+0x1a8/0x260
[ +0.000008] do_el0_svc+0x50/0x70
[ +0.000007] el0_svc+0x68/0x1a0
[ +0.000009] el0t_64_sync_handler+0x11c/0x150
[ +0.000009] el0t_64
---truncated---