iwlwifi: mvm: encapsulate power table command log message

Encapsulate the power table command logging in a separate
function to print the same information in both cases.

Signed-off-by: Alexander Bondar <alexander.bondar@intel.com>
Reviewed-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>
Signed-off-by: Johannes Berg <johannes.berg@intel.com>