iwlwifi: mvm: remove IWL_UCODE_TLV_API_BASIC_DWELL

All the supported firmwares support this API.
This includes removing dwell per band, as band is no longer a factor
in calculating the dwell. Only basic dwell is used and FW will calculate
the actual dwell time.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>