gallium: Remove unused variable in u_tests.

Fixes: 0d17b685b1 ("gallium/u_tests: add a compute shader test that clears an image")
Reviewed-by: Marek Olšák <marek.olsak@amd.com>

src/gallium/auxiliary/util/u_tests.c

@@ -792,7 +792,6 @@ test_compute_clear_image(struct pipe_context *ctx)
 {
    struct cso_context *cso;
    struct pipe_resource *cb;
-   struct pipe_sampler_view *view = NULL;
    const char *text;
 
    cso = cso_create_context(ctx, 0);