zink: do not use VK_FORMAT_D32_SFLOAT_S8_UINT without checking
Without this, we might end up trying to use VK_FORMAT_D32_SFLOAT_S8_UINT even when it's not supported... Cc: mesa-stable Reviewed-by:Mike Blumenkrantz <michael.blumenkrantz@gmail.com> Part-of: <mesa/mesa!17953>