e1000e: remove workaround for e1000 hardware

During the move of support for PCIe devices from e1000 to e1000e, this
workaround necessary only for older non-PCIe devices was mistakenly
copied into e1000e.  Remove it.
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Bruce Allan <bruce.w.allan@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

drivers/net/e1000e/netdev.c

@@ -3831,11 +3831,6 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
 		buffer_info = &tx_ring->buffer_info[i];
 		size = min(len, max_per_txd);
 
-		/* Workaround for premature desc write-backs
-		 * in TSO mode.  Append 4-byte sentinel desc */
-		if (mss && !nr_frags && size == len && size > 8)
-			size -= 4;
-
 		buffer_info->length = size;
 		/* set time_stamp *before* dma to help avoid a possible race */
 		buffer_info->time_stamp = jiffies;
@@ -3869,10 +3864,6 @@ static int e1000_tx_map(struct e1000_adapter *adapter,
 		while (len) {
 			buffer_info = &tx_ring->buffer_info[i];
 			size = min(len, max_per_txd);
-			/* Workaround for premature desc write-backs
-			 * in TSO mode.  Append 4-byte sentinel desc */
-			if (mss && f == (nr_frags-1) && size == len && size > 8)
-				size -= 4;
 
 			buffer_info->length = size;
 			buffer_info->time_stamp = jiffies;