i965/cs: Use dispatch width of 8 for cs terminate payload setup
i965/cs: Use dispatch width of 8 for cs terminate payload setup

This prevents an assertion failure in brw_fs_live_variables.cpp,
fs_live_variables::setup_one_write: Assertion `var < num_vars' failed.

Signed-off-by: Jordan Justen <a79006884ba9cf5f4f7fcbb92a15b208780d8c97@intel.com>
Reviewed-by: Jason Ekstrand <b186559eaedf698788888c8a2559b4efb4db10d6@intel.com>

metora/MesaGLSLCompiler,metora/MesaGLSLCompiler,metora/MesaGLSLCompiler