freedreno/a6xx: single cmdstream for draw+binning

freedreno/a6xx: single cmdstream for draw+binning

Now that state which is different for draw vs binning pass is split out
into different state-groups with appropriate enable_mask (so the
appropriate one is chosen for draw vs binning), switch over to using a
single cmdstream for both passes.

This should significantly lower draw overhead for CPU bound benchmarks.

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