drm/fb: use printk to print out the switching to text mode error.

using DRM_ERROR, results in people blaming the drm code for the oops, and
not looking at the oops.

(sadly yes I've gotten reports).
Signed-off-by: Dave Airlie <airlied@redhat.com>

drivers/gpu/drm/drm_fb_helper.c

@@ -264,7 +264,7 @@ bool drm_fb_helper_force_kernel_mode(void)
 int drm_fb_helper_panic(struct notifier_block *n, unsigned long ununsed,
 			void *panic_str)
 {
-	DRM_ERROR("panic occurred, switching back to text console\n");
+	printk(KERN_ERR "panic occurred, switching back to text console\n");
 	return drm_fb_helper_force_kernel_mode();
 	return 0;
 }