drm/vmwgfx: Improve on hibernation

Make it possible to hibernate also with masters that don't switch VT at
hibernation time. We save and restore modesetting state unless fbdev is
active and enabled at hibernation time.

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