mwifiex: release semaphore acquired for internal scan operation

mwifiex: release semaphore acquired for internal scan operation

If "iw connect" command is fired for station interface, when
heavy traffic is running on AP interface, internal scan operation
performed before actual association is aborted. In this case we
missed to release semaphore.

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