netfilter: nf_tables: add range expression

Inverse ranges != [a,b] are not currently possible because rules are
composites of && operations, and we need to express this:

	data < a || data > b

This patch adds a new range expression. Positive ranges can be already
through two cmp expressions:

	cmp(sreg, data, >=)
	cmp(sreg, data, <=)

This new range expression provides an alternative way to express this.

Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
diff --git a/net/netfilter/nf_tables_core.c b/net/netfilter/nf_tables_core.c
index 67259ce..7c94ce0 100644
--- a/net/netfilter/nf_tables_core.c
+++ b/net/netfilter/nf_tables_core.c
@@ -263,8 +263,13 @@
 	if (err < 0)
 		goto err7;
 
-	return 0;
+	err = nft_range_module_init();
+	if (err < 0)
+		goto err8;
 
+	return 0;
+err8:
+	nft_dynset_module_exit();
 err7:
 	nft_payload_module_exit();
 err6: