nfsd: simplify nfs4_put_deleg_lease calls

Every single caller gets the file out of the delegation, so let's do
that once in nfs4_put_deleg_lease.

Plus we'll need it there for other reasons.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Reviewed-by: Jeff Layton <jlayton@kernel.org>