Remove gen3 check introduced in r286653.

kib spotted this and noticed it's not correct.

Submitted by:	kib
Reviewed by:	dumbbell

sys/dev/drm2/i915/i915_drv.c

@@ -894,7 +894,6 @@ int intel_gpu_reset(struct drm_device *dev)
 	case 4:
 		ret = i965_do_reset(dev);
 		break;
-	case 3:
 	case 2:
 		ret = i8xx_do_reset(dev);
 		break;