drm/radeon/kms/pm: Misc fixes

- don't rest the power state in pm_init()
We already boot up to the default power state.  Note this
patch relies on:
drm/radeon/kms/pm: patch default power state with default clocks/voltages on r6xx+
To make sure the default power state matches the boot up state.

- In the pm resume path asic init will have set the power state
back to the default so reset the tracking state values.

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