xfs: remove pointless unlocked assertion

Remove this assertion about the inode not having an attr fork from
xfs_bmap_add_attrfork because the function handles that case just fine.
Weirder still, the function actually /requires/ the caller not to hold
the ILOCK, which means that its accesses are not stabilized.
Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>

fs/xfs/libxfs/xfs_bmap.c

@@ -1041,8 +1041,6 @@ xfs_bmap_add_attrfork(
 	int			logflags;	/* logging flags */
 	int			error;		/* error return value */
 
-	ASSERT(xfs_inode_has_attr_fork(ip) == 0);
-
 	mp = ip->i_mount;
 	ASSERT(!XFS_NOT_DQATTACHED(mp, ip));