[syzbot] [afs?] [net?] KCSAN: data-race in rxrpc_peer_keepalive_worker / rxrpc_send_data_packet

[David Howells]

I think that this shouldn't be a problem.  The write is:

	conn->peer->last_tx_at = ktime_get_seconds();

and the read is:

	keepalive_at = peer->last_tx_at + RXRPC_KEEPALIVE_TIME;

an approximate time is fine as we're estimating when to send a keepalive
packet if we haven't transmitted a packet in a while.

David