wcn36xx: Fix fall-through warnings for Clang

In preparation to enable -Wimplicit-fallthrough for Clang, fix a
warning by replacing a /* fall through */ comment with the new
pseudo-keyword macro fallthrough; instead of letting the code fall
through to the next case.

Notice that Clang doesn't recognize /* fall through */ comments as
implicit fall-through markings.

Link: https://github.com/KSPP/linux/issues/115Signed-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Kalle Valo <kvalo@codeaurora.org>
Link: https://lore.kernel.org/r/f932c887e013767cbdabfdddd671086e8ae63193.1605896060.git.gustavoars@kernel.org

drivers/net/wireless/ath/wcn36xx/smd.c

@@ -2570,7 +2570,7 @@ static int wcn36xx_smd_hw_scan_ind(struct wcn36xx *wcn, void *buf, size_t len)
 	case WCN36XX_HAL_SCAN_IND_FAILED:
 	case WCN36XX_HAL_SCAN_IND_DEQUEUED:
 		scan_info.aborted = true;
-		/* fall through */
+		fallthrough;
 	case WCN36XX_HAL_SCAN_IND_COMPLETED:
 		mutex_lock(&wcn->scan_lock);
 		wcn->scan_req = NULL;