zebra: tweak deletion of routes without nexthop addr

zebra: tweak deletion of routes without nexthop addr

  * zebra/zserv.c

    - zread_ipv4_delete(): Pass a null 'gate' parameter to
      rib_delete_ipv4() if the route being deleted does not specify a
      next hop IP address. We were previously passing a pointer to a
      cleared out IP address.

    - zread_ipv4_add(): Fix indentation.

From: Subbaiah Venkata <svenkata@google.com>
Signed-off-by: Avneesh Sachdev <avneesh@opensourcerouting.org>
Signed-off-by: David Lamparter <equinox@diac24.net>