gallium/tests: silence warning in compute.c

compute.c: In function ‘launch_grid’:
compute.c:435:20: warning: assignment discards ‘const’ qualifier from pointer target type [enabled by default]
         info.input = input;
                    ^

Maybe the pipe_grid_info::input field should be const void *?

Reviewed-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>

src/gallium/tests/trivial/compute.c

@@ -421,7 +421,7 @@ static void destroy_globals(struct context *ctx)
 
 static void launch_grid(struct context *ctx, const uint *block_layout,
                         const uint *grid_layout, uint32_t pc,
-                        const void *input)
+                        void *input)
 {
         struct pipe_context *pipe = ctx->pipe;
         struct pipe_grid_info info;