[NETFILTER]: make secmark_tg_destroy() static

This patch makes the needlessly global secmark_tg_destroy() static.
Signed-off-by: Adrian Bunk <bunk@kernel.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/netfilter/xt_SECMARK.c

@@ -111,7 +111,7 @@ secmark_tg_check(const char *tablename, const void *entry,
 	return true;
 }
 
-void secmark_tg_destroy(const struct xt_target *target, void *targinfo)
+static void secmark_tg_destroy(const struct xt_target *target, void *targinfo)
 {
 	switch (mode) {
 	case SECMARK_MODE_SEL: