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

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>