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

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

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.