drm/nouveau: Queue hpd_work on (runtime) resume

We need to call drm_helper_hpd_irq_event() on resume to properly detect
monitor connection / disconnection on some laptops, use hpd_work for
this to avoid deadlocks.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>