btrfs: code optimize: BTRFS_ATTR could handle the mode

All that uses BTRFS_ATTR want mode to be set at 0444 so just do
it at the define.  And few spacing alignments.

Signed-off-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Chris Mason <clm@fb.com>
diff --git a/fs/btrfs/sysfs.h b/fs/btrfs/sysfs.h
index ac46df3..531b11e 100644
--- a/fs/btrfs/sysfs.h
+++ b/fs/btrfs/sysfs.h
@@ -21,15 +21,18 @@
 }
 
 #define BTRFS_ATTR_RW(_name, _mode, _show, _store)			\
-static struct kobj_attribute btrfs_attr_##_name =			\
+	static struct kobj_attribute btrfs_attr_##_name =		\
 			__INIT_KOBJ_ATTR(_name, _mode, _show, _store)
-#define BTRFS_ATTR(_name, _mode, _show)					\
-	BTRFS_ATTR_RW(_name, _mode, _show, NULL)
+
+#define BTRFS_ATTR(_name, _show)					\
+			BTRFS_ATTR_RW(_name, 0444, _show, NULL)
+
 #define BTRFS_ATTR_PTR(_name)    (&btrfs_attr_##_name.attr)
 
 #define BTRFS_RAID_ATTR(_name, _show)					\
-static struct kobj_attribute btrfs_raid_attr_##_name =			\
+	static struct kobj_attribute btrfs_raid_attr_##_name =		\
 			__INIT_KOBJ_ATTR(_name, 0444, _show, NULL)
+
 #define BTRFS_RAID_ATTR_PTR(_name)    (&btrfs_raid_attr_##_name.attr)