rxrpc: Change rx_packet tracepoint to display securityIndex not type twice

Change the rx_packet tracepoint to display the securityIndex from the
packet header instead of displaying the type in numeric form.  There's no
need for the latter, as the display of the type in symbolic form will fall
back automatically to displaying the hex value if no symbol is available.

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