iris: Fix compute shader leak

Variant after creation with the function iris_create_shader_variant
requires to be added to variants. Otherwise there is a memory
leak after execution.

Fixes: 2024d470483("iris: Add the variant to the list as early as possible")
Signed-off-by: Mykhailo Skorokhodov <mykhailo.skorokhodov@globallogic.com>
Reviewed-by: Ian Romanick <ian.d.romanick@intel.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/12645>

src/gallium/drivers/iris/iris_program.c

@@ -2531,6 +2531,9 @@ iris_create_compute_state(struct pipe_context *ctx,
          iris_create_shader_variant(screen, NULL, IRIS_CACHE_CS,
                                     sizeof(key), &key);
 
+      /* Append our new variant to the shader's variant list. */
+      list_addtail(&shader->link, &ish->variants);
+
       if (!iris_disk_cache_retrieve(screen, uploader, ish, shader,
                                     &key, sizeof(key))) {
          iris_compile_cs(screen, uploader, &ice->dbg, ish, shader);