drm/amd/display: Fix assert observed when performing dummy p-state check

[WHY]
V.Active dram clock change workaround need a small modification for DMLv2
to ensure that the dummy p-state check doesn't fail.

Signed-off-by: David Galiffi <David.Galiffi@amd.com>
Reviewed-by: Jun Lei <Jun.Lei@amd.com>
Acked-by: Bhawanpreet Lakha <Bhawanpreet.Lakha@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>