wifi: iwlwifi: mvm: don't set the MFP flag for the GTK

In the Linux kernel, the following vulnerability has been resolved: wifi: iwlwifi: mvm: don't set the MFP flag for the GTK The firmware doesn't need the MFP flag for the GTK, it can even make the firmware crash. in case the AP is configured with: group cipher TKIP and MFPC. We would send the GTK with cipher = TKIP and MFP which is of course not possible.