UPSTREAM: gtp: use icmp_ndo_send helper

commit e0fce6f945a26d4e953a147fe7ca11410322c9fe upstream.

Because gtp is calling icmp from network device context, it should use
the ndo helper so that the rate limiting applies correctly.

Signed-off-by: Jason A. Donenfeld <Jason@zx2c4.com>
Cc: Harald Welte <laforge@gnumonks.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
(cherry picked from commit d8d268ce)
Signed-off-by: Greg Kroah-Hartman <gregkh@google.com>
Change-Id: I87cecb7368e63ad10a3a6a43d990797997019f92