drm/vmwgfx: Fix black screen and device errors when running without fbdev

drm/vmwgfx: Fix black screen and device errors when running without fbdev

commit 140bcaa23a1c37b694910424075a15e009120dbe upstream.

When we are running without fbdev, transitioning from the login screen to
X or gnome-shell/wayland will cause a vt switch and the driver will disable
svga mode, losing all modesetting resources. However, the kms atomic state
does not reflect that and may think that a crtc is still turned on, which
will cause device errors when we try to bind an fb to the crtc, and the
screen will remain black.

Fix this by turning off all kms resources before disabling svga mode.

Cc: <stable@vger.kernel.org>
Signed-off-by: Thomas Hellstrom <thellstrom@vmware.com>
Reviewed-by: Sinclair Yeh <syeh@vmware.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>