sgi-xp: xpc_partition: mark expected switch fall-throughs

In preparation to enabling -Wimplicit-fallthrough, mark switch cases
where we are expecting to fall through.
Signed-off-by: NGustavo A. R. Silva <gustavo@embeddedor.com>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>

drivers/misc/sgi-xp/xpc_partition.c

@@ -446,8 +446,10 @@ xpc_discovery(void)
 		switch (region_size) {
 		case 128:
 			max_regions *= 2;
+			/* fall through */
 		case 64:
 			max_regions *= 2;
+			/* fall through */
 		case 32:
 			max_regions *= 2;
 			region_size = 16;