conf: Fix typo and logic in conf_ports() check for port binding

Ouch, I accidentally pushed the previous change without running the
tests:

- we need to check, in conf_ports(), that udp_sock_init()
  managed to bind at least a port, not the opposite

- for -T and -U, we have no way to know if we'll manage to bind
  the port later, so never report an error for those

Fixes: 3d0de2c1d7 ("conf, tcp, udp: Exit if we fail to bind sockets for all given ports")
Signed-off-by: Stefano Brivio <sbrivio@redhat.com>

conf.c

@@ -306,6 +306,9 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg,
 			} else if (optname == 'u') {
 				if (!udp_sock_init(c, 0, af, addr, ifname, i))
 					bound_one = true;
+			} else {
+				/* No way to check in advance for -T and -U */
+				bound_one = true;
 			}
 		}
 
@@ -356,7 +359,10 @@ static void conf_ports(const struct ctx *c, char optname, const char *optarg,
 				if (!tcp_sock_init(c, af, addr, ifname, i))
 					bound_one = true;
 			} else if (optname == 'u') {
-				if (udp_sock_init(c, 0, af, addr, ifname, i))
+				if (!udp_sock_init(c, 0, af, addr, ifname, i))
+					bound_one = true;
+			} else {
+				/* No way to check in advance for -T and -U */
 				bound_one = true;
 			}
 		}