staging: lustre: osc: mark expected switch fall-through

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.

Addresses-Coverity-ID: 1077598
Signed-off-by: Gustavo A. R. Silva <garsilva@embeddedor.com>
Reviewed-by: Andreas Dilger <andreas.dilger@intel.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/staging/lustre/lustre/osc/osc_cache.c

@@ -227,6 +227,7 @@ static int osc_extent_sanity_check0(struct osc_extent *ext,
 			rc = 65;
 			goto out;
 		}
+		/* fall through */
 	default:
 		if (atomic_read(&ext->oe_users) > 0) {
 			rc = 70;