drm/nouveau: Remove useless poll_disable() call in switcheroo_set_state()

This won't do anything but potentially make us miss hotplugs. We already
call drm_kms_helper_poll_disable() in
nouveau_pmops_suspend()->nouveau_display_suspend()->nouveau_display_fini()

Signed-off-by: Lyude Paul <lyude@redhat.com>
Reviewed-by: Karol Herbst <kherbst@redhat.com>
Acked-by: Daniel Vetter <daniel@ffwll.ch>
Cc: Lukas Wunner <lukas@wunner.de>
Signed-off-by: Ben Skeggs <bskeggs@redhat.com>

drivers/gpu/drm/nouveau/nouveau_vga.c

@@ -50,7 +50,6 @@ nouveau_switcheroo_set_state(struct pci_dev *pdev,
 	} else {
 		pr_err("VGA switcheroo: switched nouveau off\n");
 		dev->switch_power_state = DRM_SWITCH_POWER_CHANGING;
-		drm_kms_helper_poll_disable(dev);
 		nouveau_switcheroo_optimus_dsm();
 		nouveau_pmops_suspend(&pdev->dev);
 		dev->switch_power_state = DRM_SWITCH_POWER_OFF;