drm/amd/display: Adjust debug msg for usb4/tbt

[Why & How]
Debug msg for usb4/tbt now is a bit confusing. Adjust it for better reading.

Reviewed-by: Jerry Zuo <jerry.zuo@amd.com>
Acked-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>