nfsd: lock state around put client and delegation in nfsd4_cb_recall

not having the state locked before putting the client/delegation causes a bug.
Also removed the comment from the function header about the state being already locked

Signed-off-by: Alexandros Batsakis <batsakis@netapp.com>
Signed-off-by: Benny Halevy <bhalevy@panasas.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>