NET: IPV4: fix error "do not initialise globals to 0"

this patch fixes below Errors reported by checkpatch
    ERROR: do not initialise globals to 0
    +int cipso_v4_rbm_optfmt = 0;

Signed-off-by: wangzhitong <wangzhitong@uniontech.com>
Signed-off-by: David S. Miller <davem@davemloft.net>