drm/amd/display: Cap certain DML values for Low Pix Clk on DCN2.1

[WHY]
In certain conditions with low pixel clock, some values in DML may go
past the max due to margining for latency hiding. This causes assertions
to get hit.

[HOW]
If the pixel clock is low and some values are high, cap it to the max.

Signed-off-by: Sung Lee <sung.lee@amd.com>
Reviewed-by: Dmytro Laktyushkin <Dmytro.Laktyushkin@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>