btrfs-progs: balance status: fix usage show long verbose

btrfs balance status supports both short and long option -v|--verbose
but usage failed to show it in its --help. This patch fixes the --help.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: David Sterba <dsterba@suse.com>

cmds/balance.c

@@ -822,7 +822,7 @@ static const char * const cmd_balance_status_usage[] = {
 	"btrfs balance status [-v] <path>",
 	"Show status of running or paused balance",
 	"",
-	"-v     be verbose",
+	"-v|--verbose     be verbose",
 	NULL
 };