xfs: Pull up xfs_attr_rmtval_invalidate

This patch pulls xfs_attr_rmtval_invalidate out of
xfs_attr_rmtval_remove and into the calling functions.  Eventually
__xfs_attr_rmtval_remove will replace xfs_attr_rmtval_remove when we
introduce delayed attributes.  These functions are exepcted to return
-EAGAIN when they need a new transaction.  Because the invalidate does
not need a new transaction, we need to separate it from the rest of the
function that does.  This will enable __xfs_attr_rmtval_remove to
smoothly replace xfs_attr_rmtval_remove later.

Signed-off-by: Allison Collins <allison.henderson@oracle.com>
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>
Acked-by: Dave Chinner <dchinner@redhat.com>