ipv6: use IS_ENABLED()

#if defined(CONFIG_FOO) || defined(CONFIG_FOO_MODULE)

can be replaced by

#if IS_ENABLED(CONFIG_FOO)

Cc: David S. Miller <davem@davemloft.net>
Signed-off-by: Cong Wang <amwang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/net/ipv6/xfrm6_policy.c b/net/ipv6/xfrm6_policy.c
index f8c4c08..f3ed8ca 100644
--- a/net/ipv6/xfrm6_policy.c
+++ b/net/ipv6/xfrm6_policy.c
@@ -20,7 +20,7 @@
 #include <net/ip.h>
 #include <net/ipv6.h>
 #include <net/ip6_route.h>
-#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
+#if IS_ENABLED(CONFIG_IPV6_MIP6)
 #include <net/mip6.h>
 #endif
 
@@ -182,7 +182,7 @@
 			fl6->flowi6_proto = nexthdr;
 			return;
 
-#if defined(CONFIG_IPV6_MIP6) || defined(CONFIG_IPV6_MIP6_MODULE)
+#if IS_ENABLED(CONFIG_IPV6_MIP6)
 		case IPPROTO_MH:
 			if (!onlyproto && pskb_may_pull(skb, nh + offset + 3 - skb->data)) {
 				struct ip6_mh *mh;