xfs: remove the same fs check from xfs_file_share_range

The VFS already does the check, and the placement of this duplicate
is in the way of the following locking rework.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Dave Chinner <david@fromorbit.com>

fs/xfs/xfs_file.c

@@ -965,9 +965,6 @@ xfs_file_share_range(
 	    IS_SWAPFILE(inode_out))
 		return -ETXTBSY;
 
-	/* Reflink only works within this filesystem. */
-	if (inode_in->i_sb != inode_out->i_sb)
-		return -EXDEV;
 	same_inode = (inode_in->i_ino == inode_out->i_ino);
 
 	/* Don't reflink dirs, pipes, sockets... */