scsi: sym53c8xx_2: sym_nvram: Mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Reviewed-by: NKees Cook <keescook@chromium.org>
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>

drivers/scsi/sym53c8xx_2/sym_nvram.c

@@ -708,6 +708,7 @@ static int sym_read_Tekram_nvram (struct sym_device *np, Tekram_nvram *nvram)
 					  data, len);
 		if (!x)
 			break;
+		/* fall through */
 	default:
 		x = sym_read_T93C46_nvram(np, nvram);
 		break;