drm/amd/display: Add AUX I2C tracing.

[Why]
Developers can find it useful if the driver can produce
AUX traces without special equipment.

[How]
Add AUX tracing.

Reviewed-by: Zhan Liu <zhan.liu@amd.com>
Acked-by: Anson Jacob <Anson.Jacob@amd.com>
Signed-off-by: Ashley Thomas <Ashley.Thomas2@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>