iomap: introduce io{read|write}64_{lo_hi|hi_lo}

In order to provide non-atomic functions for io{read|write}64 that will
use readq and writeq when appropriate. We define a number of variants
of these functions in the generic iomap that will do non-atomic
operations on pio but atomic operations on mmio.

These functions are only defined if readq and writeq are defined. If
they are not, then the wrappers that always use non-atomic operations
from include/linux/io-64-nonatomic*.h will be used.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Andy Shevchenko <andy.shevchenko@gmail.com>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Suresh Warrier <warrier@linux.vnet.ibm.com>
Cc: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>