Bluetooth: fix memory leak in error path of hci_alloc_dev()

Bluetooth: fix memory leak in error path of hci_alloc_dev()

Early failures in Bluetooth HCI UART configuration leak SRCU percpu
memory.

When device initialization fails before hci_register_dev() completes,
the HCI_UNREGISTER flag is never set. As a result, when the device
reference count reaches zero, bt_host_release() evaluates this flag as
false and falls back to a direct kfree(hdev).

Because hci_release_dev() is bypassed, the SRCU struct initialized
early in hci_alloc_dev() is never cleaned up, resulting in a leak of
percpu memory.

Fix the leak by explicitly calling cleanup_srcu_struct() in the
fallback (unregistered) branch of bt_host_release() before freeing
the device.

Reported-by: syzbot+535ecc844591e50588a5@syzkaller.appspotmail.com
Closes: https://syzkaller.appspot.com/bug?extid=535ecc844591e50588a5
Tested-by: syzbot+535ecc844591e50588a5@syzkaller.appspotmail.com
Fixes: 1d6123102e9f ("Bluetooth: hci_core: Fix use-after-free in vhci_flush()")
Signed-off-by: Bharath Reddy <kbreddy.rpbc@gmail.com>
Signed-off-by: Luiz Augusto von Dentz <luiz.von.dentz@intel.com>