wifi: iwlwifi: mvm: Fix key flags for IGTK on AP interface

When an IGTK is installed for an AP interface, there is no station
associated with it. However, the MFP flag must be set for the installed
key as otherwise the FW wouldn't use it.

Fix the security key flag to set the MFP flag also when the AP is
an AP interface and the key index matches that of an IGTK.

Fixes: 5c75a208

 ("wifi: iwlwifi: mvm: support new key API")
Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Gregory Greenman <gregory.greenman@intel.com>
Link: https://lore.kernel.org/r/20231011130030.f67005e2d4d2.I6832c6e87f3c79fff00689eb10a3a30810e1ee83@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>