drm/amd/display: DP compliance automation test fixes

Fixes:
1. Removing pending flag since we are executing teh entire flow without context switches
2. Adding stream enablment - connection between DIG BE to DIG FE during test link training

Signed-off-by: Leon Elazar <leon.elazar@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>