Don't use indirect remap functions for conf_ports()

Now that we've delayed initialization of the UDP specific "reverse" map
until udp_init(), the only difference between the various 'remap' functions
used in conf_ports() is which array they target.  So, simplify by open
coding the logic into conf_ports() with a pointer to the correct mapping
array.

Signed-off-by: David Gibson <david@gibson.dropbear.id.au>

tcp.h

@@ -29,8 +29,6 @@ void tcp_defer_handler(struct ctx *c);
 void tcp_sock_set_bufsize(const struct ctx *c, int s);
 void tcp_update_l2_buf(const unsigned char *eth_d, const unsigned char *eth_s,
 		       const uint32_t *ip_da);
-void tcp_remap_to_tap(struct ctx *c, in_port_t port, in_port_t delta);
-void tcp_remap_to_init(struct ctx *c, in_port_t port, in_port_t delta);
 
 /**
  * union tcp_epoll_ref - epoll reference portion for TCP connections