iwlwifi: mvm: rename some LMAC-specific scan functions

Some LMAC specific functions had too generic names
(i.e. *_scan_offload_*) and were hard to distinguish from functions
that are really generic.  Rename these functions to *_lmac_scan_* in
to make it more consistent and easier to read.

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