EDAC, pnd2: Sort headers alphabetically

Sort the headers in alphabetic order in order to ease
the maintenance for this part.

Signed-off-by: Andy Shevchenko <andriy.shevchenko@linux.intel.com>
Reviewed-by: Qiuxu Zhuo <qiuxu.zhuo@intel.com>
Signed-off-by: Tony Luck <tony.luck@intel.com>