- Add hooks in various entry points to perform hw/sw init for DCN6 asic
- Add dependent changes needed to enable DCN6 asic
- Update the Makefiles so that DCN6 related newly added sources are compiled

Signed-off-by: Aurabindo Pillai <aurabindo.pillai@amd.com>
Signed-off-by: Roman Li <Roman.Li@amd.com>
Reviewed-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[WHAT]
Add a KUnit test for dm_dmub_get_vbios_bounding_box() covering the
default IP-version path that returns NULL without allocating GPU memory
or issuing GPINT commands.

Assisted-by: Copilot:Claude-Opus-4.8 GPT-5.5
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

[WHAT]
Add KUnit coverage for the DMUB fused IO helpers: the
dm_dmub_aux_fused_io_callback() NULL-argument guard and the
abort_fused_io() no-DMUB-service path.

Assisted-by: Copilot:Claude-Opus-4.8 GPT-5.5
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>

Move DMUB-related functions and firmware defines from amdgpu_dm.c
into new amdgpu_dm_dmub.c and amdgpu_dm_dmub.h files to reduce
the size of amdgpu_dm.c and improve code organization.

No functional change intended.

Assisted-by: Copilot:Claude-Opus-4.6
Reviewed-by: Bhawanpreet Lakha <bhawanpreet.lakha@amd.com>
Signed-off-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Chenyu Chen <chen-yu.chen@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>