iwlwifi: mvm: add number of scan iterations and multiplier to params

As another step towards combining the scan and sched scan functions,
add parameters that tell the scan function how many iterations we want
(i.e. 1 for normal scan, more for scheduled scan) and that set the
full scan multiplier (only meaningful for LMAC).

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