cso: Store hash key in struct cso_sampler

Preparation for following changes, no functional change intended.

Reviewed-by: Nicolai Hähnle <nicolai.haehnle@amd.com>

src/gallium/auxiliary/cso_cache/cso_cache.h

@@ -129,6 +129,7 @@ struct cso_sampler {
    void *data;
    cso_state_callback delete_state;
    struct pipe_context *context;
+   unsigned hash_key;
 };
 
 struct cso_velems_state {

src/gallium/auxiliary/cso_cache/cso_context.c

@@ -1182,6 +1182,7 @@ cso_single_sampler(struct cso_context *ctx, unsigned shader_stage,
          cso->delete_state =
             (cso_state_callback) ctx->pipe->delete_sampler_state;
          cso->context = ctx->pipe;
+         cso->hash_key = hash_key;
 
          iter = cso_insert_state(ctx->cache, hash_key, CSO_SAMPLER, cso);
          if (cso_hash_iter_is_null(iter)) {