radv: Backported fixes for mesa 20.3
I went through the list in Dylan's 20.3 status email and fixed up all the RADV and ACO commits so that they apply to 20.3.
The following are on Dylan's list but not part of this MR:
c40ea24ee0radv: fix overflow when computing the SQTT buffer size
5b5cd18853radv: inhibit clock gating when tracing with SQTT
f695957421radv: move queue object to a common base object
bd98fc39aeradv: reset object base on recycled command buffers