mwifiex: fix power state out of sync problem

mwifiex: fix power state out of sync problem

It's been observed that driver's power state goes out
of sync with firmware in some corner cases. When this
happens, driver tries to download the data to firmware
assuming it's awake which causes Tx data timeout.

Main thread will process interrupt as soon as interrupt
handler fills 'int_status' variable.

This patch fixes the race issue by updating 'int_status'
at the end of mwifiex_interrupt_status().

Signed-off-by: Shengzhen Li <szli@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>