The runtime needs a queue on which to submit cache management commands.
Device-to-device blit copy already creates a queue unconditionally.
We can share this queue for both purposes.
This change restructures the BlitKernel interface to accept, rather than
create, a queue. GpuAgent creates queues as needed for both cache
management and blit compute.
Fix queue full detection in AcquireWriteIndex (<= vs <).
Change-Id: I61d0c6b9d04f2dba74872f0676ad791435778ba4
Jay Cornwall
f7ab361347