e1000e: cleanup: remove unused #define

All references to E1000_ERT_2048 have been removed.
Signed-off-by: Bruce Allan <bruce.w.allan@intel.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000e/e1000.h

@@ -78,9 +78,6 @@ struct e1000_info;
 #define E1000_MIN_ITR_USECS		10 /* 100000 irq/sec */
 #define E1000_MAX_ITR_USECS		10000 /* 100    irq/sec */
 
-/* Early Receive defines */
-#define E1000_ERT_2048			0x100
-
 #define E1000_FC_PAUSE_TIME		0x0680 /* 858 usec */
 
 /* How many Tx Descriptors do we need to call netif_wake_queue ? */