bus: fsl-mc: don't assume child devices are all fsl-mc devices

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

bus: fsl-mc: don't assume child devices are all fsl-mc devices

Changes in VFIO caused a pseudo-device to be created as child of
fsl-mc devices causing a crash [1] when trying to bind a fsl-mc
device to VFIO. Fix this by checking the device type when enumerating
fsl-mc child devices.

[1]
Modules linked in:
Internal error: Oops: 0000000096000004 [#1] PREEMPT SMP
CPU: 6 PID: 1289 Comm: sh Not tainted 6.2.0-rc5-00047-g7c46948a6e9c #2
Hardware name: NXP Layerscape LX2160ARDB (DT)
pstate: 60000005 (nZCv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
pc : mc_send_command+0x24/0x1f0
lr : dprc_get_obj_region+0xfc/0x1c0
sp : ffff80000a88b900
x29: ffff80000a88b900 x28: ffff48a9429e1400 x27: 00000000000002b2
x26: ffff48a9429e1718 x25: 0000000000000000 x24: 0000000000000000
x23: ffffd59331ba3918 x22: ffffd59331ba3000 x21: 0000000000000000
x20: ffff80000a88b9b8 x19: 0000000000000000 x18: 0000000000000001
x17: 7270642f636d2d6c x16: 73662e3030303030 x15: ffffffffffffffff
x14: ffffd59330f1d668 x13: ffff48a8727dc389 x12: ffff48a8727dc386
x11: 0000000000000002 x10: 00008ceaf02f35d4 x9 : 0000000000000012
x8 : 0000000000000000 x7 : 0000000000000006 x6 : ffff80000a88bab0
x5 : 0000000000000000 x4 : 0000000000000000 x3 : ffff80000a88b9e8
x2 : ffff80000a88b9e8 x1 : 0000000000000000 x0 : ffff48a945142b80
Call trace:
mc_send_command+0x24/0x1f0
dprc_get_obj_region+0xfc/0x1c0
fsl_mc_device_add+0x340/0x590
fsl_mc_obj_device_add+0xd0/0xf8
dprc_scan_objects+0x1c4/0x340
dprc_scan_container+0x38/0x60
vfio_fsl_mc_probe+0x9c/0xf8
fsl_mc_driver_probe+0x24/0x70
really_probe+0xbc/0x2a8
__driver_probe_device+0x78/0xe0
device_driver_attach+0x30/0x68
bind_store+0xa8/0x130
drv_attr_store+0x24/0x38
sysfs_kf_write+0x44/0x60
kernfs_fop_write_iter+0x128/0x1b8
vfs_write+0x334/0x448
ksys_write+0x68/0xf0
__arm64_sys_write+0x1c/0x28
invoke_syscall+0x44/0x108
el0_svc_common.constprop.1+0x94/0xf8
do_el0_svc+0x38/0xb0
el0_svc+0x20/0x50
el0t_64_sync_handler+0x98/0xc0
el0t_64_sync+0x174/0x178
Code: aa0103f4 a9025bf5 d5384100 b9400801 (79401260)
---[ end trace 0000000000000000 ]---