drm/amd/display: Refactor recout calculation with a more generic formula

drm/amd/display: Refactor recout calculation with a more generic formula

[Why]
Current recout calculation has a few assumptions and implementation
for MPO + ODM combine calculation is very specific. The equation has
too many cases without enough comments to document the detail.

[How]
The change remove the following assumptions:
1. When MPO is enabled, we only allow ODM Combine 2:1
2. ODM Combine always has even segment width.
3. Secondary MPO plane's pipe_ctx copies pre_odm_pipe from
its top pipe.

The change applies a generic formula with more details in comment to
document this solution so it is eaiser to learn and debug later.

Reviewed-by: Dmytro Laktyushkin <dmytro.laktyushkin@amd.com>
Acked-by: Alex Hung <alex.hung@amd.com>
Signed-off-by: Wenjing Liu <wenjing.liu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>