drm/kms/fb: use slow work mechanism for normal hotplug also.

a) slow work is always used now for any fbcon hotplug, as its not
   a fast task and is more suited to being ran under slow work.

b) attempt to not do any fbdev changes when X is running as we'll
   just mess it up. This hooks set_par to hopefully do the changes
   once X hands control to fbdev.

This also adds the nouveau/intel hotplug support.

Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/i915/i915_irq.c

@@ -266,6 +266,7 @@ static void i915_hotplug_work_func(struct work_struct *work)
 		}
 	}
 	/* Just fire off a uevent and let userspace tell us what to do */
+	intelfb_hotplug(dev, false);
 	drm_sysfs_hotplug_event(dev);
 }