[IPSEC] Turn km_event.data into a union

This patch turns km_event.data into a union.  This makes code that
uses it clearer.
  
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
diff --git a/net/xfrm/xfrm_state.c b/net/xfrm/xfrm_state.c
index 94f7416..e068bd7 100644
--- a/net/xfrm/xfrm_state.c
+++ b/net/xfrm/xfrm_state.c
@@ -835,7 +835,7 @@
 {
 	struct km_event c;
 
-	c.data = hard;
+	c.data.hard = hard;
 	c.event = XFRM_SAP_EXPIRED;
 	km_state_notify(x, &c);
 
@@ -883,8 +883,7 @@
 {
 	struct km_event c;
 
-	c.data = hard;
-	c.data = hard;
+	c.data.hard = hard;
 	c.event = XFRM_SAP_EXPIRED;
 	km_policy_notify(pol, dir, &c);