mac80211: Remove support for changing AP SMPS mode

The SMPS feature is defined in the specification only to be
used by non-AP stations and not by APs, so remove the support
for changing the AP's SMPS mode dynamically.

Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/20200131111300.891737-20-luca@coelho.fi


Signed-off-by: Johannes Berg <johannes.berg@intel.com>