drm/amd/display: Init DMUB DPIA Only for APU

drm/amd/display: Init DMUB DPIA Only for APU

[why & how]
1. There is no need to init dpia in dgpu
2. Add additional dpia flags
   a. dpia hpd dynamic control
   b. consolidated dpia link training to dp
   c. dynamic bw allocation support

Reviewed-by: Roman Li <roman.li@amd.com>
Signed-off-by: Fangzhi Zuo <Jerry.Zuo@amd.com>
Signed-off-by: Wayne Lin <wayne.lin@amd.com>
Tested-by: Dan Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>