isdn: remove extra byteswap in isdn_net_ciscohdlck_slarp_send_reply

commit a144ea4b

 [IPV4]: annotate struct in_ifaddr

Missed this extra byteswap as the isdn inlines hide the htonl inside
put_u32 which causes an extra byteswap on little-endian arches.

Signed-off-by: Harvey Harrison <harvey.harrison@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>