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

net/ipv4/cipso_ipv4.c

@@ -73,7 +73,7 @@ struct cipso_v4_map_cache_entry {
 static struct cipso_v4_map_cache_bkt *cipso_v4_cache;
 
 /* Restricted bitmap (tag #1) flags */
-int cipso_v4_rbm_optfmt = 0;
+int cipso_v4_rbm_optfmt;
 int cipso_v4_rbm_strictvalid = 1;
 
 /*