[PATCH] e1000: collision retry count too high

* For half duplex, the IEEE says collision retry count should
  be 15 not 16.  Would cause really slow transfers on some hubs
  (i.e NetGear DS108).

drivers/net/e1000/e1000_hw.h

@@ -1540,7 +1540,7 @@ struct e1000_hw {
 #define PBA_SIZE 4
 
 /* Collision related configuration parameters */
-#define E1000_COLLISION_THRESHOLD       16
+#define E1000_COLLISION_THRESHOLD       15
 #define E1000_CT_SHIFT                  4
 #define E1000_COLLISION_DISTANCE        64
 #define E1000_FDX_COLLISION_DISTANCE    E1000_COLLISION_DISTANCE