iwlwifi: mvm: abort scheduled scan on scan request

Some older versions of wpa_supplicant don't necessarily stop
scheduled scan before starting a regular scan, and there's
nothing in the API that requires it either. As a consequence
our driver's behaviour of not allowing scan while scheduled
scan was in progress broke userspace.

However, it is valid to unilaterally stop scheduled scan at
any point in time, so when a regular scan request comes just
abort the scheduled scan and run the regular scan.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Reviewed-by: Alexander Bondar <alexander.bondar@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>