Use LRU mapping policy for SDMA engines v3

[Andres Rodriguez]

Previously we discussed some issues with applying the LRU mapping policy
to the SDMA engines. Mainly, if both ring ids end up aliased to the same
HW block, the total transfer bandwith an application can achieve will be
severely impacted. E.g. an app uses one SDMA ring for upload and one for
download.

This small series prevents ring id aliasing and enables LRU mapping for the
DMA ip blocks.

This series depends on "Add support for high priority scheduling in amdgpu"