rsxx: Use fallthrough pseudo-keyword

Replace /* Fall through. */ comment with the new pseudo-keyword macro
fallthrough[1].

[1] https://www.kernel.org/doc/html/v5.7/process/deprecated.html?highlight=fallthrough#implicit-switch-case-fall-throughSigned-off-by: Gustavo A. R. Silva <gustavoars@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/rsxx/core.c

@@ -439,7 +439,7 @@ static void card_state_change(struct rsxx_cardinfo *card,
 	case CARD_STATE_FAULT:
 		dev_crit(CARD_TO_DEV(card),
 			"Hardware Fault reported!\n");
-		/* Fall through. */
+		fallthrough;
 
 	/* Everything else, detach DMA interface if it's attached. */
 	case CARD_STATE_SHUTDOWN: