i965/cs: Set invocation counts based on max_cs_threads

i965/cs: Set invocation counts based on max_cs_threads

For ES, we set the max counts based on SIMD8, which is currently
accurate.

For desktop GL, we set the max counts based on SIMD16, which can fail
in some cases where a SIMD16 program is not currently supported.
Therefore, this value is not currently accurate, but will work fine in
many cases, and lets us run more test cases. Eventually we want to
always be able to generate a SIMD16 program.

Signed-off-by: Jordan Justen <jordan.l.justen@intel.com>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>