drm/radeon/kms/pm: patch default power state with default clocks/voltages on r6xx+

The default power state does not always match the default clocks and voltage
for a particular card.  The information in the firmware info table is correct
and should be used in preference to the info the default power state.

Signed-off-by: Alex Deucher <alexdeucher@gmail.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>