mwifiex: use timeout variant for wait_event_interruptible

It has been observed that system hangs during suspend, if host
sleep activation fails due to a missing interrupt from firmware.
Use timeout variant, so that the thread will be woken up when
timer expires.

Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Bing Zhao <bzhao@marvell.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>