ospfd: fix cli shown in running config when turning off ldp-sync

ospfd: fix cli shown in running config when turning off ldp-sync

LDP-Sync is automatically enabled on interfaces when turned on in
router ospf context.   The user can remove ldp-sync from running
on an interface, by issuing a "no ip ospd mpls ldp-sync" command.
To remove all ldp-sync interface commands the user must delete
ldp-sync at the router level.  The code was not correctly removing
the config.   This PR fixes that issue.   Now the extra cli
ldp-sync commands are removed when ldp-sync is disabled.

Signed-off-by: Lynne Morrison <lynne.morrison@ibm.com>