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>
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index bd172e1..d2cadb5 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -1866,7 +1866,9 @@
 				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;