ixgbe: Cleanup the use of tabs and spaces

Cleans up the whitespace issues noticed during code review where
a mix of tabs and spaces were used for indentation.
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>
Tested-by: NPhil Schmitt <phillip.j.schmitt@intel.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>