i965: Remove unneeded VS workaround stalls on Baytrail.

i965: Remove unneeded VS workaround stalls on Baytrail.

According to the workarounds list, these stalls aren't needed on
production Baytrail systems.  Piglit confirms that as well.

These cause a small slowdown when we are sending a large number of small
batches to the GPU.  Removing these improves performance by up to 5% on
some CPU bound SynMark tests (Batch[4-7], DrvState1, HdrBloom,
Multithread, ShMapPcf).

Signed-off-by: Gregory Hunt <greg.hunt@mobica.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>