Bluetooth: btrtl: fix out of bounds memory access

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

Bluetooth: btrtl: fix out of bounds memory access

The problem is detected by KASAN.
btrtl driver uses private hci data to store 'struct btrealtek_data'.
If btrtl driver is used with btusb, then memory for private hci data
is allocated in btusb. But no private data is allocated after hci_dev,
when btrtl is used with hci_h5.

This commit adds memory allocation for hci_h5 case.

==================================================================
BUG: KASAN: slab-out-of-bounds in btrtl_initialize+0x6cc/0x958 [btrtl]
Write of size 8 at addr ffff00000f5a5748 by task kworker/u9:0/76

Hardware name: Pine64 PinePhone (1.2) (DT)
Workqueue: hci0 hci_power_on [bluetooth]
Call trace:
dump_backtrace+0x9c/0x128
show_stack+0x20/0x38
dump_stack_lvl+0x48/0x60
print_report+0xf8/0x5d8
kasan_report+0x90/0xd0
__asan_store8+0x9c/0xc0
[btrtl]
h5_btrtl_setup+0xd0/0x2f8 [hci_uart]
h5_setup+0x50/0x80 [hci_uart]
hci_uart_setup+0xd4/0x260 [hci_uart]
hci_dev_open_sync+0x1cc/0xf68 [bluetooth]
hci_dev_do_open+0x34/0x90 [bluetooth]
hci_power_on+0xc4/0x3c8 [bluetooth]
process_one_work+0x328/0x6f0
worker_thread+0x410/0x778
kthread+0x168/0x178
ret_from_fork+0x10/0x20

Allocated by task 53:
kasan_save_stack+0x3c/0x68
kasan_save_track+0x20/0x40
kasan_save_alloc_info+0x68/0x78
__kasan_kmalloc+0xd4/0xd8
__kmalloc+0x1b4/0x3b0
hci_alloc_dev_priv+0x28/0xa58 [bluetooth]
hci_uart_register_device+0x118/0x4f8 [hci_uart]
h5_serdev_probe+0xf4/0x178 [hci_uart]
serdev_drv_probe+0x54/0xa0
really_probe+0x254/0x588
__driver_probe_device+0xc4/0x210
driver_probe_device+0x64/0x160
__driver_attach_async_helper+0x88/0x158
async_run_entry_fn+0xd0/0x388
process_one_work+0x328/0x6f0
worker_thread+0x410/0x778
kthread+0x168/0x178
ret_from_fork+0x10/0x20

Last potentially related work creation:
kasan_save_stack+0x3c/0x68
__kasan_record_aux_stack+0xb0/0x150
kasan_record_aux_stack_noalloc+0x14/0x20
__queue_work+0x33c/0x960
queue_work_on+0x98/0xc0
hci_recv_frame+0xc8/0x1e8 [bluetooth]
h5_complete_rx_pkt+0x2c8/0x800 [hci_uart]
h5_rx_payload+0x98/0xb8 [hci_uart]
h5_recv+0x158/0x3d8 [hci_uart]
hci_uart_receive_buf+0xa0/0xe8 [hci_uart]
ttyport_receive_buf+0xac/0x178
flush_to_ldisc+0x130/0x2c8
process_one_work+0x328/0x6f0
worker_thread+0x410/0x778
kthread+0x168/0x178
ret_from_fork+0x10/0x20

Second to last potentially related work creation:
kasan_save_stack+0x3c/0x68
__kasan_record_aux_stack+0xb0/0x150
kasan_record_aux_stack_noalloc+0x14/0x20
__queue_work+0x788/0x960
queue_work_on+0x98/0xc0
__hci_cmd_sync_sk+0x23c/0x7a0 [bluetooth]
__hci_cmd_sync+0x24/0x38 [bluetooth]
btrtl_initialize+0x760/0x958 [btrtl]
h5_btrtl_setup+0xd0/0x2f8 [hci_uart]
h5_setup+0x50/0x80 [hci_uart]
hci_uart_setup+0xd4/0x260 [hci_uart]
hci_dev_open_sync+0x1cc/0xf68 [bluetooth]
hci_dev_do_open+0x34/0x90 [bluetooth]
hci_power_on+0xc4/0x3c8 [bluetooth]
process_one_work+0x328/0x6f0
worker_thread+0x410/0x778
kthread+0x168/0x178
ret_from_fork+0x10/0x20
==================================================================