drm/radeon: add a quirk for a XFX R9 270X

[ Upstream commit bcb31eba4a4ea356fd61cbd5dec5511c3883f57e ]

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=76490



Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>