drm/amdgpu: add irq sources for vcn v4_0

Add the interrupt source packet definitions for VCN4.

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>