wifi: rtw88: delete timer and free skb queue when unloading

Fix possible crash and memory leak on driver unload by deleting
TX purge timer and freeing C2H queue in 'rtw_core_deinit()',
shrink critical section in the latter by freeing COEX queue
out of TX report lock scope.

Reviewed-by: Ping-Ke Shih <pkshih@realtek.com>
Signed-off-by: Dmitry Antipov <dmantipov@yandex.ru>
Signed-off-by: Kalle Valo <kvalo@kernel.org>
Link: https://lore.kernel.org/r/20230628072327.167196-1-dmantipov@yandex.ru