iwlwifi: mvm: advertise only HW-supported ciphers

After the new ciphers CCMP-256 and GCMP-128/256 were implemented,
wpa_supplicant could start negotiating them and use the software
implementation. This, however, breaks D3 behaviour in the driver
since it means that WoWLAN will not be possible.

To avoid breaking that feature, advertise only ciphers that the
hardware supports.

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