Client: always pass a Fh to _do_filelock

Client: always pass a Fh to _do_filelock

We weren't passing in the Fh as a signal we were releasing locks (ie, don't
remove the lock ranges in question rather than adding htem to our accounting).
But that was a little weird and doesn't work when we're pulling perms out of
the Fh.

Signed-off-by: Greg Farnum <gfarnum@redhat.com>