drm/radeon: add a quirk for Toshiba Satellite L20-183

drm/radeon: add a quirk for Toshiba Satellite L20-183

BugLink: http://bugs.launchpad.net/bugs/1702118
commit acfd6ee4fa7ebeee75511825fe02be3f7ac1d668 upstream.

Fixes resume from suspend.

bug: https://bugzilla.kernel.org/show_bug.cgi?id=196121
Reported-by: Przemek <soprwa@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>