[XFRM]: Fix XFRMGRP_REPORT to use correct multicast group.

XFRMGRP_REPORT uses 0x10 which is a group that belongs
to events. The correct value is 0x20.
We should really be using xfrm_nlgroups going forward; it was tempting
to delete the definition of XFRMGRP_REPORT but it would break at
least iproute2.
Signed-off-by: NJ Hadi Salim <hadi@cyberus.ca>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/xfrm.h

@@ -357,7 +357,7 @@ struct xfrm_user_report {
 #define XFRMGRP_EXPIRE		2
 #define XFRMGRP_SA		4
 #define XFRMGRP_POLICY		8
-#define XFRMGRP_REPORT		0x10
+#define XFRMGRP_REPORT		0x20
 #endif
 
 enum xfrm_nlgroups {