mt76: mt7615: fix .add_beacon_offload()

ieee80211_beacon_get_template() returns NULL when beacon state is disabled,
so beacon_offload cannot be disabled for some devices.
Signed-off-by: Ryder Lee <ryder.lee@mediatek.com>
Signed-off-by: Felix Fietkau <nbd@nbd.name>

drivers/net/wireless/mediatek/mt76/mt7615/mcu.c

@@ -702,6 +702,9 @@ mt7615_mcu_add_beacon_offload(struct mt7615_dev *dev,
 	};
 	struct sk_buff *skb;
 
+	if (!enable)
+		goto out;
+
 	skb = ieee80211_beacon_get_template(hw, vif, &offs);
 	if (!skb)
 		return -EINVAL;
@@ -731,6 +734,7 @@ mt7615_mcu_add_beacon_offload(struct mt7615_dev *dev,
 	}
 	dev_kfree_skb(skb);
 
+out:
 	return mt76_mcu_send_msg(&dev->mt76, MCU_EXT_CMD_BCN_OFFLOAD, &req,
 				 sizeof(req), true);
 }
@@ -1164,8 +1168,8 @@ mt7615_mcu_uni_add_beacon_offload(struct mt7615_dev *dev,
 			__le16 tim_ie_pos;
 			__le16 csa_ie_pos;
 			__le16 bcc_ie_pos;
-			/* 0: enable beacon offload
-			 * 1: disable beacon offload
+			/* 0: disable beacon offload
+			 * 1: enable beacon offload
 			 * 2: update probe respond offload
 			 */
 			u8 enable;
@@ -1188,6 +1192,9 @@ mt7615_mcu_uni_add_beacon_offload(struct mt7615_dev *dev,
 	};
 	struct sk_buff *skb;
 
+	if (!enable)
+		goto out;
+
 	skb = ieee80211_beacon_get_template(mt76_hw(dev), vif, &offs);
 	if (!skb)
 		return -EINVAL;
@@ -1212,6 +1219,7 @@ mt7615_mcu_uni_add_beacon_offload(struct mt7615_dev *dev,
 	}
 	dev_kfree_skb(skb);
 
+out:
 	return mt76_mcu_send_msg(&dev->mt76, MCU_UNI_CMD_BSS_INFO_UPDATE,
 				 &req, sizeof(req), true);
 }