freedreno: add non-draw batches for compute/blit

freedreno: add non-draw batches for compute/blit

Get rid of "gmem" (ie. tiling) ringbuffer, and just emit setup commands
directly to "draw" ringbuffer for compute (and in future for blits not
using the 3d pipe).  This way we can have a simple flat cmdstream buffer
and bypass setup related to 3d pipe.

Signed-off-by: Rob Clark <robdclark@gmail.com>