i965/skl: Add production thread counts and URB size

i965/skl: Add production thread counts and URB size

This patch adjusts the SKL values to the best known values we have.

v2: Remove HS/DS/CS fields. Adding this makes most sense to add to the
GEN9_FEATURES macro, however, doing that would require updating BXT values, and
Jordan requested I not do that. Conveniently, this request makes a lot of sense
wrt to stable backport as HS, and DS do not even exist there.

Cc: mesa-stable@lists.freedesktop.org
Signed-off-by: Ben Widawsky <ben@bwidawsk.net>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>