With the exception of the default tess levels only ever accessed
by the default tcs shader, the LDS_INFO const buffer was only accessed by vtx
instructions, and not through kcache. No idea why really, but use this to our
advantage by not using a constant buffer slot for it. This just requires us to
throw the default tess levels into the "normal" driver const buffer instead.
Alternatively, could acesss those constants via vtx instructions too, but then
we couldn't use a ordinary ureg prog accessing them as constants and would have
to generate that directly when compiling the default tcs shader. (Another
alternative would be to put all lds info into the ordinary driver const
buffer, albeit we'd maybe need to increase the fixed size as it can't fit
alongside the ucp since vs needs access to the lds info too.)

Tested-by: Konstantin Kharlamov <hi-angel@yandex.ru>
Dave Airlie <airlied@redhat.com>