netfilter: xtables: remove __pure annotation

sparse complains:
ip_tables.c:361:27: warning: incorrect type in assignment (different modifiers)
ip_tables.c:361:27:    expected struct ipt_entry *[assigned] e
ip_tables.c:361:27:    got struct ipt_entry [pure] *

doesn't change generated code.
Signed-off-by: NFlorian Westphal <fw@strlen.de>
Signed-off-by: NPablo Neira Ayuso <pablo@netfilter.org>

net/ipv4/netfilter/arp_tables.c

@@ -240,7 +240,7 @@ get_entry(const void *base, unsigned int offset)
 	return (struct arpt_entry *)(base + offset);
 }
 
-static inline __pure
+static inline
 struct arpt_entry *arpt_next_entry(const struct arpt_entry *entry)
 {
 	return (void *)entry + entry->next_offset;

net/ipv4/netfilter/ip_tables.c

@@ -276,7 +276,7 @@ static void trace_packet(const struct sk_buff *skb,
 }
 #endif
 
-static inline __pure
+static inline
 struct ipt_entry *ipt_next_entry(const struct ipt_entry *entry)
 {
 	return (void *)entry + entry->next_offset;

net/ipv6/netfilter/ip6_tables.c

@@ -305,7 +305,7 @@ static void trace_packet(const struct sk_buff *skb,
 }
 #endif
 
-static inline __pure struct ip6t_entry *
+static inline struct ip6t_entry *
 ip6t_next_entry(const struct ip6t_entry *entry)
 {
 	return (void *)entry + entry->next_offset;