drm/vmwgfx: Remove the user resource destructor check

We were checking that the resource destructor matched that of the
intended object type, to make sure the looked up resource was of the
right type.

But we already have an object type check in place which makes sure the
resource is of the right type.

Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Reviewed-by: Deepak Rawat <drawat@vmware.com>