netfilter: ipset: whitespace and coding fixes detected by checkpatch.pl

include/linux/netfilter/ipset/ip_set.h

include/linux/netfilter/ipset/ip_set_ahash.h

include/linux/netfilter/ipset/ip_set_timeout.h

include/linux/netfilter/ipset/pfxlen.h

net/netfilter/ipset/ip_set_bitmap_ipmac.c

net/netfilter/ipset/ip_set_core.c

net/netfilter/ipset/ip_set_hash_net.c

net/netfilter/ipset/ip_set_hash_netiface.c

net/netfilter/ipset/ip_set_hash_netport.c

net/netfilter/ipset/pfxlen.c

net/netfilter/xt_set.c