r600/sb: hit the scheduler with a big hammer to avoid lds splits.

r600/sb: hit the scheduler with a big hammer to avoid lds splits.

This tries to avoid an lds queue read getting scheduled separately
from an lds ret read, the non-sb code uses the same style of hammer,
this isn't foolproof.

We can do better, but it's a bit tricky, as you have to scan ahead
and either schedule more lds oq moves and more lds reads and that
could lead to you running out of space anyways.

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