drm/amd/display: add renoir specific watermark range and clk helper

Doing this allows us to split it for diffrent asics. This design will
be helpful for future Asciis.

Signed-off-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>