radv/android: Use buffer metadata to determine scanout compat.

These days we don't always allocate scanout compatible textures anymore.
That does mean we have to fix the radv android WSI though.

Fixes: b1444c9c "radv: Implement VK_ANDROID_native_buffer."
Acked-by: Samuel Pitoiset <samuel.pitoiset@gmail.com>
(cherry picked from commit 3bf48741)