iwlwifi: mvm: combine p2p and station mac context functions

Instead of having two nearly identical functions to send the mac
context commands, use a single way that can handle both the p2p and
!p2p cases.

Signed-off-by: Luciano Coelho <luciano.coelho@intel.com>
Reviewed-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>