iwlwifi: mvm: set up initial SMPS/NSS station info

When a station is added, we need to tell the firmware what
the SMPS settings and number of streams are. After having
the initial data, the firmware will track future changes
by itself.

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