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>