nfs4: update stateid on read with proxy adapter

since we do support proxy-io with nfsv4.0 let be spec complaint and
renew the state.

RELEASE NOTES:
with proxy IO on READ dcache can support NFSv4.0 clients such as RHEL5 or mac osx 10.9 (OS X Mavericks)

Acked-by: Gerd Behrmann
Target: master
Require-notes: yes
Require-book: no