tu: Fix stale tu_render_pass_attachment::store_stencil with dyn rendering

Attachment initialization helpers expect zeroed memory by default.

Fixes a hang when running Subnautica with TU_DEBUG="gmem".
See: https://gitlab.freedesktop.org/mesa/mesa/-/issues/8702#note_1932003

Fixes: ed125e6cca
("tu: Initial support for dynamic rendering")

Signed-off-by: Danylo Piliaiev <dpiliaiev@igalia.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/25592>

src/freedreno/vulkan/tu_pass.cc

@@ -1063,6 +1063,7 @@ static void
 tu_setup_dynamic_attachment(struct tu_render_pass_attachment *att,
                             struct tu_image_view *view)
 {
+   *att = {};
    att->format = view->vk.format;
    att->samples = (VkSampleCountFlagBits) view->image->layout->nr_samples;