iwlwifi: mvm: Add DC2DC_CONFIG_CMD (0x83) cmd & TLV

Add DC2DC_CONFIG_CMD (0x83) cmd.

Add IWL_UCODE_TLV_CAPA_DC2DC_CONFIG_SUPPORT tlv.

The command allows the driver get & set the DCDC's frequency tune.
(freq_tune is the divider that is used to calculate the actual DCDC's
clock rate)
The command always returns the current/updated frequency tune values of
the DCDC.

Signed-off-by: Matti Gottlieb <matti.gottlieb@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>