drm/amd/display: Add wm ranges to clk_mgr

[WHY & HOW]
Having watermark ranges saved inside clk_mgr to be
available for debug at all times would be useful.
Add it to the clk_mgr_internal struct for reference.
Only populated for Renoir, unused for other asics.

Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Yongqiang Sun <yongqiang.sun@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>