mkfs: enable rt quota options

Now that the kernel supports quota and realtime devices, allow people to
format filesystems with permanent quota options.

Signed-off-by: "Darrick J. Wong" <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
diff --git a/mkfs/xfs_mkfs.c b/mkfs/xfs_mkfs.c
index b644022..b141e2c 100644
--- a/mkfs/xfs_mkfs.c
+++ b/mkfs/xfs_mkfs.c
@@ -2650,12 +2650,6 @@
 		cli->sb_feat.exchrange = true;
 	}
 
-	if (cli->sb_feat.qflags && cli->xi->rt.name) {
-		fprintf(stderr,
-_("persistent quota flags not supported with realtime volumes\n"));
-				usage();
-	}
-
 	/*
 	 * Persistent quota flags requires metadir support because older
 	 * kernels (or current kernels with old filesystems) will reset qflags