iwlwifi: mvm: scan dwell time corrections

Use only basic dwell time (10 ms for active scan and 110 for passive),
regardless of the number of the probes and the band, if it is
supported by the FW. The FW will add 3 ms for each probe sent and 10
ms for low band channels.
Add a TLV flag to indicate such support in FW.

This fix is needed to fix few bugs regarding scans that take too much time.

Signed-off-by: David Spinadel <david.spinadel@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>