drm/amd/display: Blank HUBP during pixel data blank for DCN30 v2

[Why]
Prior commit "Blank HUBP during pixel data blank for DCN30"
missed the call to set_disp_pattern_generator from
set_crtc_test_pattern, which re-exposed the issue for which
we initially blocked active-only p-state switching.

[How]
 - remove dcn30_blank_pixel_data, set dcn30 back to dcn20 version
 - new hwss funciton set_disp_pattern_generator
 - dcn20 version just calls opp_set_disp_pattern_generator
 - dcn30 version implements the HUBP blank

Signed-off-by: Joshua Aberback <joshua.aberback@amd.com>
Reviewed-by: Aric Cyr <Aric.Cyr@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>