i965/gs: Set static_vertex_count unconditionally on GEN8+

We always have NIR, so there's no reason for the check.

Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

src/mesa/drivers/dri/i965/brw_gs.c

@@ -96,7 +96,7 @@ brw_codegen_gs_prog(struct brw_context *brw,
                                &c.prog_data.base.base, false);
 
    if (brw->gen >= 8) {
-      c.prog_data.static_vertex_count = !gp->program.Base.nir ? -1 :
+      c.prog_data.static_vertex_count =
          nir_gs_count_vertices(gp->program.Base.nir);
    }