drm/amd/display: Add missing shifts and masks for dpp registers on dcn2

[Why]
The register CM_TEST_DEBUG_DATA is used in dpp1_program_input_csc, which is
called from dpp2_cnv_setup, but the shifts and masks for the fields of that
register are not initialized for dcn2. This causes all reads of that register
to return 0.

Signed-off-by: Joshua Aberback <joshua.aberback@amd.com>
Reviewed-by: Jaehyun Chung <Jaehyun.Chung@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>