drm/radeon: add a dpm quirk for Sapphire Radeon R9 270X 2GB GDDR5

[ Upstream commit 5dfc71bc44d91d1620505c064fa22b0b3db58a9d ]

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>