libceph: use CEPH_MON_PORT when the specified port is 0

Similar to userspace, don't bail with "parse_ips bad ip ..." if the
specified port is port 0, instead use port CEPH_MON_PORT (6789, the
default monitor port).
Signed-off-by: Ilya Dryomov <ilya.dryomov@inktank.com>
Reviewed-by: Sage Weil <sage@inktank.com>

net/ceph/messenger.c

@@ -1866,7 +1866,9 @@ int ceph_parse_ips(const char *c, const char *end,
 				port = (port * 10) + (*p - '0');
 				p++;
 			}
-			if (port > 65535 || port == 0)
+			if (port == 0)
+				port = CEPH_MON_PORT;
+			else if (port > 65535)
 				goto bad;
 		} else {
 			port = CEPH_MON_PORT;