Add a driver to configure the XO-1 RTC via CS5536 MSRs, to be used as a

Add a driver to configure the XO-1 RTC via CS5536 MSRs, to be used as a
system wakeup source via olpc-xo1-pm.

Device detection is based on finding the relevant device tree node.

Signed-off-by: Daniel Drake <dsd@laptop.org>
Acked-by: Andres Salomon <dilinger@queued.net>
Acked-by: Grant Likely <grant.likely@secretlab.ca>
Reviewed-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: "H. Peter Anvin" <hpa@zytor.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>