drm/amd/display: Limit dcn32 to 1950Mhz display clock

[why]
Hardware team recommends we limit dispclock to 1950Mhz for all DCN3.2.x

[how]
Limit to 1950 when initializing clocks.

Tested-by: Mark Broadworth <mark.broadworth@amd.com>
Reviewed-by: Alvin Lee <Alvin.Lee2@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Jun Lei <jun.lei@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>