xfs: simplify extent lookup in xfs_can_free_eofblocks

xfs_can_free_eofblocks just cares if there is an extent beyond EOF.
Replace the call to xfs_bmapi_read with a xfs_iext_lookup_extent
as we've already checked that extents are read in earlier.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Darrick J. Wong <djwong@kernel.org>
Signed-off-by: Chandan Babu R <chandanbabu@kernel.org>