ntb: ntb_hw_intel: use io-64-nonatomic instead of in-driver hacks

Now that ioread64 and iowrite64 are available in io-64-nonatomic,
we can remove the hack at the top of ntb_hw_intel.c and replace it
with an include.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Acked-by: Dave Jiang <dave.jiang@intel.com>
Acked-by: Allen Hubbe <Allen.Hubbe@dell.com>
Acked-by: Jon Mason <jdmason@kudzu.us>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>