drm/amd/display: revise Start/End SDP data

[why & how]
We need to implement the VSC packet rev4 that is required by PSRSU.

Follow the eDP 1.5 spec pg. 257

changes in v2:
-------------------
- set vsc packet rev2 for PSR1

Cc: Chandan Vurdigerenataraj <chandan.vurdigerenataraj@amd.com>

Signed-off-by: David Zhang <dingchen.zhang@amd.com>
Acked-by: Leo Li <sunpeng.li@amd.com>
Reviewed-by: Harry Wentland <harry.wentland@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>