netfilter: nft_set_pipapo: make the symbol 'nft_pipapo_get' static

Fix the following sparse warning:

net/netfilter/nft_set_pipapo.c:739:6: warning: symbol 'nft_pipapo_get' was not declared. Should it be static?

Fixes: 3c4287f6 ("nf_tables: Add set type for arbitrary concatenation of ranges")
Signed-off-by: Chen Wandun <chenwandun@huawei.com>
Acked-by: Stefano Brivio <sbrivio@redhat.com>
Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>

net/netfilter/nft_set_pipapo.c

@@ -736,8 +736,8 @@ static struct nft_pipapo_elem *pipapo_get(const struct net *net,
  * @elem:	nftables API element representation containing key data
  * @flags:	Unused
  */
-void *nft_pipapo_get(const struct net *net, const struct nft_set *set,
-		     const struct nft_set_elem *elem, unsigned int flags)
+static void *nft_pipapo_get(const struct net *net, const struct nft_set *set,
+			    const struct nft_set_elem *elem, unsigned int flags)
 {
 	return pipapo_get(net, set, (const u8 *)elem->key.val.data,
 			  nft_genmask_cur(net));