xfs: improve local fork verification

Call the data/attr local fork verifiers as soon as we are ready for them.
This keeps them close to the code setting up the forks, and avoids a
few branches later on.  Also open code xfs_inode_verify_forks in the
only remaining caller.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Brian Foster <bfoster@redhat.com>
Reviewed-by: Darrick J. Wong <darrick.wong@oracle.com>
Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>