nfsd4: move minorversion to client

The minorversion seems more a property of the client than the callback
channel.

Some time we should probably also enforce consistent minorversion usage
from the client; for now, this is just a cosmetic change.

Signed-off-by: J. Bruce Fields <bfields@redhat.com>

diff --cc fs/nfsd/nfs4callback.c
Simple merge

diff --cc fs/nfsd/nfs4state.c
Simple merge

diff --cc fs/nfsd/state.h
Simple merge