drm/amd/display: Trigger DP2 Sequence With Uncertified Cable

DP2 sequence is triggered only if VESA certified cable is detected.

Force DP2 sequence with uncertified cable for testing purpose.

Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Reviewed-by: Wenjing Liu <Wenjing.Liu@amd.com>
Acked-by: Stylon Wang <stylon.wang@amd.com>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>