mwifiex: fix failed to reconnect after interface disabled/enabled

Recent patch "mwifiex: fix NULL pointer" skips extended scan event
handling when suspend is in progress. It created a problem for scan
after interface disabled/enabled case.

This patch solves the problem by checking netif_running() status.

Fixes:16d25da9 ("mwifiex: fix NULL pointer dereference during suspend")
Signed-off-by: Amitkumar Karwar <akarwar@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>