asm-generic: temporarily add back asm-generic/io-64-nonatomic*.h

New users of these files still start showing up in linux-next, so it's
better to have a migration strategy. All existing users as of 4.3-rc4
are converted to use linux/io-64-nonatomic-*.h, and after 4.4-rc1
we can change all the new ones that have come in since, and then
remove this file again.

Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Reported-by: LKP project <lkp@linux.intel.com>