drm/amd/display: Move dio files into dio folder

[why]
Refactor the code of dio to unit test.

[how]
Moved files to respective folders and changed cMakeLists and makefiles.

Acked-by: Rodrigo Siqueira <rodrigo.siqueira@amd.com>
Signed-off-by: Jerry Zuo <jerry.zuo@amd.com>
Signed-off-by: Bhuvanachandra Pinninti <bpinnint@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>