drm/radeon: Add MSI quirk for gateway RS690

commit 3a6d59df80897cc87812b6826d70085905bed013 upstream.

Fixes another system on:
https://bugs.freedesktop.org/show_bug.cgi?id=37679

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>