iwlwifi: mvm: remove vif argument from power_update_mac

The power update function looks at all current vifs to determine the power
policy. It doesn't use the current vif. Instead the value was overwritten
and used internally.

Signed-off-by: Arik Nemtsov <arikx.nemtsov@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>