drm/amd/display: Remove i2caux folder

[Why]
It is huge, unmaintainable, needlessly layered, and obsolete

[How]
Remove it.  All of it.  Also remove the i2caux struct in
dc_context and the code that created and destructed it

Signed-off-by: David Francis <David.Francis@amd.com>
Reviewed-by: Harry Wentland <Harry.Wentland@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>