nfsd4: split lockstateid/openstateid release logic

The flags here attempt to make the code more general, but I find it
actually just adds confusion.

I think it's clearer to separate the logic for the open and lock cases
entirely.  And eventually we may want to separate the stateowner and
stateid types as well, as many of the fields aren't shared between the
lock and open cases.

Also move to eliminate forward references.

Start with the stateid's.

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