drm/radeon/dpm: handle voltage info fetching on hawaii

Some hawaii cards use a different method to fetch the
voltage info from the vbios.

bug:
https://bugs.freedesktop.org/show_bug.cgi?id=74250

Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
Cc: stable@vger.kernel.org
1 file changed