mwifiex: complete blocked power save handshake in main process

Power save handshake with firmware might be blocked by on-going
data transfer.
this patch check the PS status in main process and complete
previous blocked PS handshake.
this patch also remove redudant check before call
mwifiex_check_ps_cond function.

Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Shengzhen Li <szli@marvell.com>
Tested-by: Xinming Hu <huxm@marvell.com>
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>