iwlwifi: mvm: combine SSID functions for sched and regular scans

Now that both scheduled scan and regular scan SSID populating
functions do the same thing, they can be combined into a single
function.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>