nfsd: reshuffle some code

No change in behavior, I'm just moving some code around to avoid forward
references in a following patch.

(To do someday: figure out how to split up nfs4state.c.  It's big and
disorganized.)

Signed-off-by: J. Bruce Fields <bfields@redhat.com>
Signed-off-by: Chuck Lever <chuck.lever@oracle.com>