drm/virtio: fix object leak when drm_gem_handle_create() fails

In the Linux kernel, the following vulnerability has been resolved: drm/virtio: fix object leak when drm_gem_handle_create() fails virtio_gpu_gem_create() owns the reference taken by virtio_gpu_object_create(). On the drm_gem_handle_create() error path it calls drm_gem_object_release() instead of dropping that reference. drm_gem_object_release() is the inverse of drm_gem_object_init() and does not touch the reference count or call obj->funcs->free(), so it is only correct as the last step of a destructor, as in virtio_gpu_cleanup_object(). Using it here leaves the bo at refcount 1 with no remaining reference, so virtio_gpu_free_object() never runs and the shmem pages, sg table and virtio_gpu_object are leaked. Since virtio_gpu_object_create() has already set bo->created, VIRTIO_GPU_CMD_RESOURCE_UNREF is not queued either, leaking the host-side resource and the resource id. drm_gem_handle_create_tail() drops the handle reference on all of its internal error paths, so the caller only has to drop its own. Use drm_gem_object_put(), matching the success path below.