DRM framebuffer removal broken since 13803132

[Thomas Hellstrom]

Hi!

The commit

From 13803132818cf8084d169617be060fd8e3411a98 Mon Sep 17 00:00:00 2001
From: Maarten Lankhorst <maarten.lankhorst at linux.intel.com>
Date: Wed, 9 Sep 2015 16:40:56 +0200
Subject: [PATCH] drm/core: Preserve the framebuffer after removing it.

badly breaks vmwgfx multimon since the crtcs are no longer turned off at
framebuffer removal,
which is part of the user-space contract.

Also isn't this a security issue, since at, for example, Xorg crash, the
crtcs can be left scanning out from memory
DRM no longer owns?

/Thomas