xfs: switch xfs_attrmulti_attr_get to lazy attr buffer allocation

Let the low-level attr code only allocate the needed buffer size
for xfs_attrmulti_attr_get instead of allocating the upper bound
at the top of the call chain.
Suggested-by: Dave Chinner <dchinner@redhat.com>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Dave Chinner <dchinner@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>

fs/xfs/xfs_ioctl.c

@@ -481,10 +481,6 @@ xfs_attrmulti_attr_get(
 	if (*len > XFS_XATTR_SIZE_MAX)
 		return -EINVAL;
 
-	args.value = kmem_zalloc_large(*len, 0);
-	if (!args.value)
-		return -ENOMEM;
-
 	error = xfs_attr_get(&args);
 	if (error)
 		goto out_kfree;