[PATCH split] Improve pipe split between amdgpu and amdkfd

[Andres Rodriguez]

This is a split of patches that are ready to land from the series:
Add support for high priority scheduling in amdgpu v8

I've included Felix and Alex's feedback from the thread above. This includes:
 * Separate MEC_HPD_SIZE rename into a separate patch (patch 01)
 * Added a patch to fix the kgd_hqd_load bug Felix pointed out (patch 06)
 * Fixes for various off-by-one errors
 * Use gfx_v8_0_deactivate_hqd

Only comment I didn't address was changing the queue allocation policy for
gfx9 (similar to gfx7/8). See inline reply in that thread for more details
on why this was skipped.