VCN 4.0.3 does not HDP flush with RRMT enabled. Instead, mmsch
will do the HDP flush.

This change is necessary for VCN v4.0.3, no need for backward compatibility
Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Signed-off-by: Jane Jian <Jane.Jian@amd.com>
Reviewed-by: Hawking Zhang <Hawking.Zhang@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>
(cherry picked from commit 49cfaebe)