drm/radeon/kms: fix up dce6 display watermark calc for dpm
drm/radeon/kms: fix up dce6 display watermark calc for dpm

Calculate the low and high watermarks based on the low and high
clocks for the current power state.  The dynamic pm hw will select
the appropriate watermark based on the internal dpm state.

Signed-off-by: Alex Deucher <08dc22c6156113f2deff178e35e3ed9b24d6af9e@amd.com>

KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs,KristFoundation/Programs