intel/cs: Push subgroup ID instead of base thread ID

We're going to want subgroup ID for SPIR-V subgroups eventually anyway.
We really only want to push one and calculate the other from it.  It
makes a bit more sense to push the subgroup ID because it's simpler to
calculate and because it's a real API thing.  The only advantage to
pushing the base thread ID is to avoid a single SHL in the shader.

Reviewed-by: Iago Toral Quiroga <itoral@igalia.com>

src/intel/compiler/brw_compiler.h

@@ -552,7 +552,7 @@ enum brw_param_builtin {
    BRW_PARAM_BUILTIN_TESS_LEVEL_INNER_X,
    BRW_PARAM_BUILTIN_TESS_LEVEL_INNER_Y,
 
-   BRW_PARAM_BUILTIN_THREAD_LOCAL_ID,
+   BRW_PARAM_BUILTIN_SUBGROUP_ID,
 };
 
 #define BRW_PARAM_BUILTIN_CLIP_PLANE(idx, comp) \