MFP: Remove mac80211 workaround of IGTK in monitor netdev

mac80211 can now figure out which key to use for injected frames (in
most cases), so we can remove the workaround for configuring IGTK on the
monitor interface that is used for injecting frames.

hostapd/driver_nl80211.c

@@ -325,11 +325,6 @@ static int i802_set_encryption(const char *iface, void *priv, const char *alg,
 	if (ret < 0)
 		return ret;
 
-	if (strcmp(alg, "IGTK") == 0) {
-		ret = nl_set_encr(drv->monitor_ifidx, drv, alg, addr, idx, key,
-				  key_len, txkey);
-	}
-
 	return ret;
 }