btrfs: code optimize: BTRFS_ATTR_RW could set the mode

BTRFS_ATTR_RW could set the mode and be inline with BTRFS_ATTR

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c
index a1c1088..e6a5e7d 100644
--- a/fs/btrfs/sysfs.c
+++ b/fs/btrfs/sysfs.c
@@ -401,7 +401,7 @@
 
 	return ret;
 }
-BTRFS_ATTR_RW(label, 0644, btrfs_label_show, btrfs_label_store);
+BTRFS_ATTR_RW(label, btrfs_label_show, btrfs_label_store);
 
 static ssize_t btrfs_nodesize_show(struct kobject *kobj,
 				struct kobj_attribute *a, char *buf)