drm/amdgpu: take ownership of per-pipe configuration v3

Make amdgpu the owner of all per-pipe state of the HQDs.

This change will allow us to split the queues between kfd and amdgpu
with a queue granularity instead of pipe granularity.

This patch fixes kfd allocating an HDP_EOP region for its 3 pipes which
goes unused.

v2: support for gfx9
v3: fix gfx7 HPD intitialization

Reviewed-by: Edward O'Callaghan <funfunctor@folklore1984.net>
Reviewed-by: Felix Kuehling <Felix.Kuehling@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Andres Rodriguez <andresx7@gmail.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>