Layout is a state resource, nfsd should check it too.

v2, drop unneeded updating in nfsd4_renew()
v3, fix compile error without CONFIG_NFSD_PNFS
Signed-off-by: NKinglong Mee <kinglongmee@gmail.com>
Signed-off-by: NJ. Bruce Fields <bfields@redhat.com>