drm/amd/display: Add interface to capture expected HW state from SW state

drm/amd/display: Add interface to capture expected HW state from SW state

[Why]
To debug certain issues, such as underflow, it is common practice to
dump the HW state of all registers for analysis. The first thing to
check with the dump is to ensure all values are programmed as expected
according to SW state.

[How]
Add interface to DC to capture expected HW register values based on SW
state.

Reviewed-by: Dillon Varone <dillon.varone@amd.com>
Signed-off-by: George Shen <george.shen@amd.com>
Signed-off-by: Ivan Lipski <ivan.lipski@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>