igb: misc whitespace/formatting cleanups

This patch is intended to hold several whitespace, formatting, and
comment cleanups that have been found while cleaning up the igb driver.

Signed-off-by: Alexander Duyck <alexander.h.duyck@intel.com>
Acked-by: Peter P Waskiewicz Jr <peter.p.waskiewicz.jr@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Signed-off-by: David S. Miller <davem@davemloft.net>