[TCP] H-TCP: fix integer overflow

When using H-TCP with a single flow on a 500Mbit connection (or less
actually), alpha can exceed 65000, so alpha needs to be a u32.
Signed-off-by: NGavin McCullagh <gavin.mccullagh@nuim.ie>
Signed-off-by: NDoug Leith <doug.leith@nuim.ie>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>

net/ipv4/tcp_htcp.c

@@ -23,7 +23,7 @@ module_param(use_bandwidth_switch, int, 0644);
 MODULE_PARM_DESC(use_bandwidth_switch, "turn on/off bandwidth switcher");
 
 struct htcp {
-	u16	alpha;		/* Fixed point arith, << 7 */
+	u32	alpha;		/* Fixed point arith, << 7 */
 	u8	beta;           /* Fixed point arith, << 7 */
 	u8	modeswitch;     /* Delay modeswitch until we had at least one congestion event */
 	u32	last_cong;	/* Time since last congestion event end */