Add a quick ethtool test for interrupts using the SW interrupt.
Also, change the loopback test (for now) to not report failure.

Change-Id: Id8ef154b82475e3163087a8d1df01dfec4d529fc
Signed-off-by: Shannon Nelson <shannon.nelson@intel.com>
Signed-off-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Tested-by: Kavindya Deegala <kavindya.s.deegala@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>