drm/amdgpu: increase AMDGPU_MAX_HWIP_RINGS

[WA] Increase AMDGPU_MAX_HWIP_RINGS to 64 to support more compute
ring resource. Later need redesign with queue/prirority/scheduler
factors to reduce AMDGPU_MAX_HWIP_RINGS.

Signed-off-by: James Zhu <James.Zhu@amd.com>
Acked-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Alex Deucher <alexander.deucher@amd.com>