CVE-2022-50481 cxl: fix possible null-ptr-deref in cxl_guest_init_afu|adapter()

In the Linux kernel, the following vulnerability has been resolved: cxl: fix possible null-ptr-deref in cxlguestinitafu|adapter If deviceregister fails in cxlregisterafu|adapter, the device is not added, deviceunregister can not be called in the error path, otherwise it will cause a null-ptr-dere...