drm/kms/fb: provide a 1024x768 fbcon if no outputs found.

If we get no outputs setup provide a 1024x768 fbcon, with
this + radeon hotplug stuff I can plug a monitor in after startup
and get to see stuff.

Last thing is to add some sort of timer for non-hpd outputs like
VGA etc.
Signed-off-by: NDave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_fb_helper.c

@@ -821,7 +821,9 @@ int drm_fb_helper_single_fb_probe(struct drm_fb_helper *fb_helper,
 	if (crtc_count == 0 || sizes.fb_width == -1 || sizes.fb_height == -1) {
 		/* hmm everyone went away - assume VGA cable just fell out
 		   and will come back later. */
-		return 0;
+		DRM_ERROR("Cannot find any crtc or sizes - going 1024x768\n");
+		sizes.fb_width = sizes.surface_width = 1024;
+		sizes.fb_height = sizes.surface_height = 768;
 	}
 
 	/* push down into drivers */