drm/amd/display: USB-C to HDMI dongle not light

RV1 support only USB-C active DP-2-HDMI dongle. HPD short pulse is
generated only for DP signal.

When processing HPD short pulse, it must be DP active dongle. No need
for I2C-Over-AUX detection.

v2: Add description

Signed-off-by: Hersen Wu <hersenxs.wu@amd.com>
Reviewed-by: Tony Cheng <Tony.Cheng@amd.com>
Acked-by: Harry Wentland <Harry.Wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>