e1000e: i219 fix unit hang on reset and runtime D3

Unit hang may occur if multiple descriptors are available in the rings
during reset or runtime suspend. This state can be detected by testing
bit 8 in the FEXTNVM7 register. If this bit is set and there are pending
descriptors in one of the rings, we must flush them prior to reset. Same
applies entering runtime suspend.

Signed-off-by: Yanir Lubetkin <yanirx.lubetkin@intel.com>
Reviewed-by: Alexander Duyck <alexander.h.duyck@redhat.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>