netfilter: ipset: fix boolreturn.cocci warnings

net/netfilter/xt_set.c:196:9-10: WARNING: return of 0/1 in function 'set_match_v3' with return type bool
net/netfilter/xt_set.c:242:9-10: WARNING: return of 0/1 in function 'set_match_v4' with return type bool

 Return statements in functions returning bool should use
 true/false instead of 1/0.
Generated by: scripts/coccinelle/misc/boolreturn.cocci

CC: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Fengguang Wu <fengguang.wu@intel.com>
Acked-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>