[TXY][v2] net/ena: update driver version to 1.1.2

[Kamal Mostafa]

BugLink: http://bugs.launchpad.net/bugs/1664312

This patch set updates the Amazon ENA driver in the Ubuntu GA kernels from
version 1.0.2 to version 1.1.2 (specifically, the net-next backport set that
we've been carrying in linux-aws).

For Xenial and Yakkety, these are cherry-picks from mainline with one
small backport change (context).  For Trusty, there are a few minor backport
changes (context, and s/READ_ONCE/ACCESS_ONCE/).

I have smoke-tested functionality and network performance.

 -Kamal