iwlwifi: mvm: rename unified_scan symbols to just scan

All scans are using the unified APIs now, so using "unified" in the
symbols is useless and just make them much longer and the main
difference between scans now is LMAC vs. UMAC.  Remove "unified" from
all relevant symbols.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>