[LLC]: add multicast support for datagrams

Allow mulitcast reception of datagrams (similar to UDP).
All sockets bound to the same SAP receive a clone.

Signed-off-by: Stephen Hemminger <shemminger@osdl.org>
Signed-off-by: David S. Miller <davem@davemloft.net>
diff --git a/include/net/llc_if.h b/include/net/llc_if.h
index a05d04a..c608812 100644
--- a/include/net/llc_if.h
+++ b/include/net/llc_if.h
@@ -79,6 +79,10 @@
 	return llc_mac_null(addr->mac) && !addr->lsap;
 }
 
+static inline int llc_mac_multicast(const u8 *mac)
+{
+	return is_multicast_ether_addr(mac);
+}
 /**
  *	llc_mac_match - determines if two mac addresses are the same
  *	@mac1: First mac address to compare.