mwifiex: notify cfg80211 about scan abort

Driver sends a series of scan commands to firmware to serve a
user scan request. If an intermediate scan command fails, driver
aborts the scan but it is not being informed to cfg80211. This
will cause issues in applications performing periodic scans.
Fix this by informing scan abort.

Signed-off-by: Cathy Luo <cluo@marvell.com>
Signed-off-by: Ganapathi Bhat <gbhat@marvell.com>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>