radeonsi: enable shader culling for indirect draws

It was mistakenly disabled, decreasing performance a lot.

Only valid for Mesa 21.3.

Reviewed-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
Cc: 21.3 <mesa-stable@lists.freedesktop.org>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/13539>

src/gallium/drivers/radeonsi/si_state_draw.cpp

@@ -2210,6 +2210,7 @@ static void si_draw(struct pipe_context *ctx,
             si_resource(indirect->indirect_draw_count)->TC_L2_dirty = false;
          }
       }
+      total_direct_count = INT_MAX; /* just set something other than 0 to enable shader culling */
    } else {
       total_direct_count = min_direct_count = draws[0].count;