svc: Move accept call to svc_xprt_received to common code

Now that the svc_xprt_received function handles transports, the call
to svc_xprt_received in the xpo_tcp_accept function can be moved to
common code.

Signed-off-by: Tom Tucker <tom@opengridcomputing.com>
Acked-by: Neil Brown <neilb@suse.de>
Reviewed-by: Chuck Lever <chuck.lever@oracle.com>
Reviewed-by: Greg Banks <gnb@sgi.com>
Signed-off-by: J. Bruce Fields <bfields@citi.umich.edu>