nfsd: add a forget_client set_clnt routine

...that relies on the client_lock instead of client_mutex.

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

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

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

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