Bluetooth: Use fallthrough pseudo-keyword

Replace the existing /* fall through */ comments and its variants with
the new pseudo-keyword macro fallthrough[1]. Also, remove unnecessary
fall-through markings when it is the case.

[1] https://www.kernel.org/doc/html/latest/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-through

Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Marcel Holtmann <marcel@holtmann.org>
diff --git a/drivers/bluetooth/hci_ll.c b/drivers/bluetooth/hci_ll.c
index d9a4c6c..8bfe024 100644
--- a/drivers/bluetooth/hci_ll.c
+++ b/drivers/bluetooth/hci_ll.c
@@ -219,7 +219,7 @@ static void ll_device_want_to_wakeup(struct hci_uart *hu)
 		 * perfectly safe to always send one.
 		 */
 		BT_DBG("dual wake-up-indication");
-		/* fall through */
+		fallthrough;
 	case HCILL_ASLEEP:
 		/* acknowledge device wake up */
 		if (send_hcill_cmd(HCILL_WAKE_UP_ACK, hu) < 0) {