ixgbevf: Fix code comments and whitespace

Fix the code comments to align with drivers/net/ code commenting style,
as well as whitespace issues.  The whitespace issues resolve checkpatch
errors, like lines exceeding 80 chars (except for strings) and the use
of tabs where possible.

CC: <kernel-team@fb.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>
Tested-by: Phil Schmitt <phillip.j.schmitt@intel.com>