Allow architecture specific data in struct platform_device V3.

With this patch struct pdev_archdata is added to struct
platform_device, similar to struct dev_archdata in found in
struct device. Useful for architecture code that needs to
keep extra data associated with each platform device.

Struct pdev_archdata is different from dev.platform_data, the
convention is that dev.platform_data points to driver-specific
data. It may or may not be required by the driver. The format
of this depends on driver but is the same across architectures.

The structure pdev_archdata is a place for architecture specific
data. This data is handled by architecture specific code (for
example runtime PM), and since it is architecture specific it
should _never_ be touched by device driver code. Exactly like
struct dev_archdata but for platform devices.

[rjw: This change is for power management mostly and that's why it
 goes through the suspend tree.]
Signed-off-by: Magnus Damm <damm@igel.co.jp>
Acked-by: Kevin Hilman <khilman@deeprootsystems.com>
Acked-by: Greg Kroah-Hartman <gregkh@suse.de>
Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>