mwifiex: fix the incorrect WARN_ON during suspend

During system suspend, there is a kernel WARNING issued if there
is a pending command present. By marking the wait queue disabled
after calling the command completion routine fixes it.

Signed-off-by: Vishal Thanki <vishalthanki@gmail.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>