drm/amdgpu/vcn: add vcn support for VCN4_0_3

Add vcn support for VCN4_0_3.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Reviewed-by: Leo Liu <leo.liu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>