zink: delete unused zink_surface member

I think this was used before imageless_framebuffer became a requirement?

Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/19307>

src/gallium/drivers/zink/zink_surface.c

@@ -121,7 +121,6 @@ init_surface_info(struct zink_surface *surface, struct zink_resource *res, VkIma
       if (zink_kopper_has_srgb(cdt))
          surface->info.format[1] = ivci->format == cdt->formats[0] ? cdt->formats[1] : cdt->formats[0];
    }
-   surface->info_hash = _mesa_hash_data(&surface->info, sizeof(surface->info));
 }
 
 static struct zink_surface *
@@ -389,7 +388,6 @@ zink_rebind_surface(struct zink_context *ctx, struct pipe_surface **psurface)
    /* update for imageless fb */
    surface->info.flags = res->obj->vkflags;
    surface->info.usage = res->obj->vkusage;
-   surface->info_hash = _mesa_hash_data(&surface->info, sizeof(surface->info));
    simple_mtx_unlock(&res->surface_mtx);
    return true;
 }

src/gallium/drivers/zink/zink_types.h

@@ -1310,7 +1310,6 @@ struct zink_surface {
    VkImageViewCreateInfo ivci;
    VkImageViewUsageCreateInfo usage_info;
    struct zink_surface_info info;
-   uint32_t info_hash;
    bool is_swapchain;
    VkImageView image_view;
    void *dt;