btrfs-progs: corrupt block, add break after option U

Resolves-Coverity-CID: 1258793
Reviewed-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: David Sterba <dsterba@suse.cz>

btrfs-corrupt-block.c

@@ -1068,6 +1068,7 @@ int main(int ac, char **av)
 				break;
 			case 'U':
 				chunk_tree = 1;
+				break;
 			case 'i':
 				inode = arg_strtou64(optarg);
 				break;