net: ena: introduce Low Latency Queues data structures according to ENA spec

net: ena: introduce Low Latency Queues data structures according to ENA spec

BugLink: http://bugs.launchpad.net/bugs/1798182
Low Latency Queues(LLQ) allow usage of device's memory for descriptors
and headers. Such queues decrease processing time since data is already
located on the device when driver rings the doorbell.

Signed-off-by: Arthur Kiyanovski <akiyano@amazon.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
(cherry picked from commit a7982b8ec947052df6d4467b3a81571f02f528e0 linux-next)
Signed-off-by: Kamal Mostafa <kamal@canonical.com>
Acked-by: Khalid Elmously <khalid.elmously@canonical.com>
Acked-by: Seth Forshee <seth.forshee@canonical.com>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>