r600/sb: use different stacks for tracking lds and queue usage.

r600/sb: use different stacks for tracking lds and queue usage.

The normal ssa renumbering isn't sufficient for LDS queue access,
this uses two stacks, one for the lds queue, and one for the
lds r/w ordering.

The LDS oq values are incremented in their use in a linear
fashion.
The LDS rw values are incremented in their definitions and used
in the next lds operation to ensure reordering doesn't occur.

Acked-By: Roland Scheidegger <sroland@vmware.com>
Signed-off-by: Dave Airlie <airlied@redhat.com>