drm/amd/display: Prepare for Fused I2C-over-AUX

[Why]
Passive DP-HDMI dongles use I2C-over-AUX protocol which is currently
not supported using HDCP Locality Check FW path.

[How]
Prepare code for switching to I2C-over-AUX protocol. Passive dongle
detection to be added in another commit.

Reviewed-by: Alvin Lee <alvin.lee2@amd.com>
Signed-off-by: Dominik Kaszewski <dominik.kaszewski@amd.com>
Signed-off-by: Ray Wu <ray.wu@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>