drm/amd/display: combine public interfaces into single header

[Why]
We want to better encapsulate all driver-fw dependencies into a single
file.

[How]
Combine all the headers under inc folder into a single header

Signed-off-by: Anthony Koo <Anthony.Koo@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Qingqing Zhuo <qingqing.zhuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Get DMUB registers from ASIC specific structs

[Why]
These values can differ per ASIC and should follow the full DC style
register programming model.

[How]
Define a common list and fill in the common list separately for
dcn20 and dcn21.

Unlike DC we're not using designated initializers for better compiler
compatibility since this resides in the DMUB service.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Rodrigo Siqueira <Rodrigo.Siqueira@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

drm/amd/display: Add the DMUB service

The DMUB service is the interface to the DMCUB.

It's required to support Renoir features so it will be enabled and
compiled automatically when the Renoir display engine is enabled via
CONFIG_DRM_AMD_DC_DCN2_1.

DMUB code will initially be guarded by CONFIG_DRM_AMD_DC_DMUB and later
switched to CONFIG_DRM_AMD_DC_DCN2_1 with the config option dropped.

Signed-off-by: Nicholas Kazlauskas <nicholas.kazlauskas@amd.com>
Reviewed-by: Hersen Wu <hersenxs.wu@amd.com>
Acked-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>