btrfs-progs: subvol create: remove v from getopt

The option 'v' was mistakenly added in
2ed161bd28 but there's no such option for
create at the moment, remove it.

Signed-off-by: David Sterba <dsterba@suse.com>

cmds-subvolume.c

@@ -128,7 +128,7 @@ static int cmd_subvol_create(int argc, char **argv)
 	DIR	*dirstream = NULL;
 
 	while (1) {
-		int c = getopt(argc, argv, "c:i:v");
+		int c = getopt(argc, argv, "c:i:");
 		if (c < 0)
 			break;