nl80211: Always register management frames handler

If registering WMM-AC ADDTS response action frame or WMM-AC DELTS
action frame fails, the management frame handler is not being
registered. This results with a segmentation fault when trying to
unsubscribe the handler when the interface is removed.
Fix it by always registering the handler and just returning a negative
value to note that the action frame could not be registered.

This fixes an issue introduced in the commit
dfa8787833f0b237f954b01233cad3527f3d4805 ('nl80211: Implement
add_ts/del_ts ops').

Signed-off-by: Avraham Stern <avraham.stern@intel.com>

src/drivers/driver_nl80211.c

@@ -1830,11 +1830,11 @@ static int nl80211_mgmt_subscribe_non_ap(struct i802_bss *bss)
 
 	/* WMM-AC ADDTS Response */
 	if (nl80211_register_action_frame(bss, (u8 *) "\x11\x01", 2) < 0)
-		return -1;
+		ret = -1;
 
 	/* WMM-AC DELTS */
 	if (nl80211_register_action_frame(bss, (u8 *) "\x11\x02", 2) < 0)
-		return -1;
+		ret = -1;
 
 	/* Radio Measurement - Neighbor Report Response */
 	if (nl80211_register_action_frame(bss, (u8 *) "\x05\x05", 2) < 0)