[DLM] force removal of user lockspace

Check if the FORCEFREE flag has been provided from user space.  If so, set
the force option to dlm_release_lockspace() so that any remaining locks
will be freed.

Signed-off-by: David Teigland <teigland@redhat.com>
Signed-off-by: Steven Whitehouse <swhiteho@redhat.com>