drm/vmwgfx: Reorder device takedown somewhat

To take down the MOB and GMR memory types, the driver may have to issue
fence objects and thus make sure that the fence manager is taken down
after those memory types.
Reorder device init accordingly.

Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>