drm/amd/display: Remove hw w/a toggle if on DP2/HPO

[why&how]
Applying a hw w/a only relevant to DIG FIFO causing corruption
using HPO, do not apply the w/a if on DP2/HPO

Reviewed-by: Charlene Liu <charlene.liu@amd.com>
Signed-off-by: Ausef Yousof <Ausef.Yousof@amd.com>
Signed-off-by: Zaeem Mohamed <zaeem.mohamed@amd.com>
Tested-by: Daniel Wheeler <daniel.wheeler@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>