[ Upstream commit db9b2e0af605e7c994784527abfd9276cabd718a ]

Fix the rxrpc_recvmsg tracepoint to handle being called with a NULL call
parameter.

Fixes: a25e21f0 ("rxrpc, afs: Use debug_ids rather than pointers in traces")
Signed-off-by: NDavid Howells <dhowells@redhat.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>
Signed-off-by: NGreg Kroah-Hartman <gregkh@linuxfoundation.org>