vulkan/wsi: fix double free on error condition
On error during wsi_wl_surface_create_swapchain(), wsi_wl_swapchain_chain_free() is called, followed by vk_free() of the recently freed chain. Move the vk_free() to wsi_wl_swapchain_destroy() to avoid the double free.
Fixes dEQP-VK.wsi.wayland.swapchain.simulate_oom.*