drm/amdgpu: Simplify aquavanjram instance mapping

Simplify so as to use the same sequence to assign logical to physical
ids for all IPs.

Signed-off-by: Lijo Lazar <lijo.lazar@amd.com>
Acked-by: Leo Liu <leo.liu@amd.com>
Tested-by: James Zhu <James.Zhu@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>