e1000: remove the check: skb->len<=0

There is no case skb->len would be 0 or 'negative'.
Remove the check.

Signed-off-by: Yongjian Xu <xuyongjiande@gmail.com>
Tested-by: Aaron Brown <aaron.f.brown@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>

drivers/net/ethernet/intel/e1000/e1000_main.c

@@ -3105,11 +3105,6 @@ static netdev_tx_t e1000_xmit_frame(struct sk_buff *skb,
 	 */
 	tx_ring = adapter->tx_ring;
 
-	if (unlikely(skb->len <= 0)) {
-		dev_kfree_skb_any(skb);
-		return NETDEV_TX_OK;
-	}
-
 	/* On PCI/PCI-X HW, if packet size is less than ETH_ZLEN,
 	 * packets may get corrupted during padding by HW.
 	 * To WA this issue, pad all small packets manually.