ixgbe: Resolve warnings produced in W=2 builds

This patch resolves warnings produced by ixgbe in W=2 kernel
builds. There are missing-field-initializers warnings and shadow
warnings. None of these point to any deeper problem, so just
resolve them so any new warnings get analyzed.

Signed-off-by: Mark Rustad <mark.d.rustad@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>