Bluetooth: use flexible-array member instead of zero-length array

Fix the following coccicheck warning:

net/bluetooth/msft.c:37:6-13: WARNING use flexible-array member instead
net/bluetooth/msft.c:42:6-10: WARNING use flexible-array member instead
net/bluetooth/msft.c:52:6-10: WARNING use flexible-array member instead

Signed-off-by: Qiheng Lin <linqiheng@huawei.com>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>

net/bluetooth/msft.c

@@ -34,12 +34,12 @@ struct msft_le_monitor_advertisement_pattern {
 	__u8 length;
 	__u8 data_type;
 	__u8 start_byte;
-	__u8 pattern[0];
+	__u8 pattern[];
 };
 
 struct msft_le_monitor_advertisement_pattern_data {
 	__u8 count;
-	__u8 data[0];
+	__u8 data[];
 };
 
 struct msft_cp_le_monitor_advertisement {
@@ -49,7 +49,7 @@ struct msft_cp_le_monitor_advertisement {
 	__u8 rssi_low_interval;
 	__u8 rssi_sampling_period;
 	__u8 cond_type;
-	__u8 data[0];
+	__u8 data[];
 } __packed;
 
 struct msft_rp_le_monitor_advertisement {