reiserfs: Fix mistake in down_write() conversion

Fix a mistake in commit 0719d343
(reiserfs: Fix reiserfs lock <-> i_xattr_sem dependency inversion)
that has converted a down_write() into a down_read() accidentally.
Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Christian Kujau <lists@nerdbynature.de>
Cc: Alexander Beregalov <a.beregalov@gmail.com>
Cc: Chris Mason <chris.mason@oracle.com>
Cc: Ingo Molnar <mingo@elte.hu>

fs/reiserfs/xattr.c

@@ -495,7 +495,7 @@ reiserfs_xattr_set_handle(struct reiserfs_transaction_handle *th,
 		return PTR_ERR(dentry);
 	}
 
-	down_read(&REISERFS_I(inode)->i_xattr_sem);
+	down_write(&REISERFS_I(inode)->i_xattr_sem);
 
 	reiserfs_write_lock(inode->i_sb);