i40e/i40evf: try again after failure

i40e/i40evf: try again after failure

BugLink: http://bugs.launchpad.net/bugs/1547674
This is the "Don't Give Up" patch.  Previously the
driver could fail an allocation, and then possibly stall
a queue forever, by never coming back to continue receiving
or allocating buffers.

With this patch, the driver will keep polling trying to allocate
receive buffers until it succeeds.  This should keep all receive
queues running even in the face of memory pressure.

Also update copyright year in file header.

Change-ID: I2b103d1ce95b9831288a7222c3343ffa1988b81b
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
(cherry picked from net-next commit c2e245ab1e9a61e66217aafea66c7dc6481f12f0)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>