i40e: Fix TSO with more than 8 frags per segment issue

i40e: Fix TSO with more than 8 frags per segment issue

The hardware has some limitations the driver needs to adhere to,
that we found in extended testing.
  1) no more than 8 descriptors per packet on the wire
  2) no header can span more than 3 descriptors

If one of these events occurs, the hardware will generate an internal
error and freeze the Tx queue.

This patch linearizes the skb to avoid these situations.

Change-ID: I37dab7d3966e14895a9663ec4d0aaa8eb0d9e115
Signed-off-by: Anjali Singhai Jain <[email protected]>
Tested-by: Jim Young <[email protected]>
Signed-off-by: Jeff Kirsher <[email protected]>