vulkan: Add a vk_video_session_finish() helper

It's always better if init/finish come in pairs.

Reviewed-by: Dave Airlie <airlied@redhat.com>
Reviewed-by: Hyunjun Ko <zzoon@igalia.com>
Reviewed-by: David Rosca <david.rosca@amd.com>
Part-of: <https://gitlab.freedesktop.org/mesa/mesa/-/merge_requests/36646>

src/intel/vulkan/anv_video.c

@@ -64,7 +64,7 @@ anv_DestroyVideoSessionKHR(VkDevice _device,
    if (!_session)
       return;
 
-   vk_object_base_finish(&vid->vk.base);
+   vk_video_session_finish(&vid->vk);
    vk_free2(&device->vk.alloc, pAllocator, vid);
 }