iwlwifi: mvm: use proper sta_addr in firmware API

There's no point to declare an address as a __le32/__le16
and then only take a pointer to it anyway, change that to
just a sta_addr[ETH_ALEN].

Signed-off-by: Johannes Berg <johannes.berg@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>