netdevice: change net_device->promiscuity/allmulti to unsigned int

The comments of dev_set_allmulti/promiscuity() is that "While the count in
the device remains above zero...". So negative count is useless.
Fix the type of the counter from "int" to "unsigned int".
Signed-off-by: NWang Chen <wangchen@cn.fujitsu.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

include/linux/netdevice.h

@@ -595,8 +595,8 @@ struct net_device
 	int			uc_promisc;
 	struct dev_addr_list	*mc_list;	/* Multicast mac addresses	*/
 	int			mc_count;	/* Number of installed mcasts	*/
-	int			promiscuity;
-	int			allmulti;
+	unsigned int		promiscuity;
+	unsigned int		allmulti;
 
 
 	/* Protocol specific pointers */