iwlwifi: mvm: clean up AUX station handling

The auxiliary station is being handled using the internal
station helper functions, clean that up and make the helpers
static.

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Emmanuel Grumbach <emmanuel.grumbach@intel.com>

diff --cc drivers/net/wireless/iwlwifi/mvm/mac80211.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/mvm/sta.c
Simple merge

diff --cc drivers/net/wireless/iwlwifi/mvm/sta.h
Simple merge