XOP-440: Pull in upstream netback patches

Pull in the 5 patch series to enable IPv6 checksum offload and GSO.
Also add pending patches to fix fragment detection in checksum setup and
netback guest-receive-side flow control.
CA-122810: Speculative fixes

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
CA-122810: Another speculative fix

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
CA-122812: Chop out IPv6 patches to see if that helps

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
CA-122812: Chop out flow control patch and re-instate IPv6 patches

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
I hate git add!

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
CA-122812: Swap req_cons for req_prod in the value we write to re_event -
           should hopefully avoid the lock-up.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
CA-122812: Add some locking and debug

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
CA-122812: Remove locking as it seemed to cause deadlock

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
CA-122812: Forget the hysteresis as it netfront doesn't seem to
 	   sufficiently refill the ring. Just wake the external queue
	   when the internal one goes empty.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
CA-122812: Fixed. XOP-440 patch sent upstream and re-synced here.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
XOP-440: Final upstream patches

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
More patches from upstream:

- Add NAPI fixes
- Two patches to fix most WHQL offload test issues
  - One undiagnosed issue still remains with IPv6 packets containing
    option headers

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Linux core networking seems to have problems parsing some IPv6 headers
created by Windows HCK tests. This patch adds an optimization to netback
that avoids touching that parsing code in the VM-to-VM case.

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Update previously committed patch after upstream view

Signed-off-by: Paul Durrant <paul.durrant@citrix.com>
Merge commit '7b1a663e3e7133ff8fa93232127db3edef8d34d5'