rxrpc: Remove the flags from the rxrpc_skb tracepoint

Remove the flags from the rxrpc_skb tracepoint as we're no longer going to
be using this for the transmission buffers and so marking which are
transmission buffers isn't going to be necessary.

Note that this also remove the rxrpc skb flag that indicates if this is a
transmission buffer and so the count is not updated for the moment.

Signed-off-by: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org