clk: RK808: add clkout driver for RK808

This is the initial version of the RK808 PMIC.  This is a power management
IC for multimedia products.  It provides regulators that are able to
supply power to processor cores and other components.  The chip provides
other modules including RTC, Clockout.

Signed-off-by: Chris Zhong <zyw@rock-chips.com>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Tested-by: Doug Anderson <dianders@chromium.org>
Tested-by: Heiko Stuebner <heiko@sntech.de>
Cc: Pawel Moll <pawel.moll@arm.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Ian Campbell <ijc+devicetree@hellion.org.uk>
Cc: Samuel Ortiz <sameo@linux.intel.com> says:
Cc: Alessandro Zummo <a.zummo@towertech.it>
Cc: Olof Johansson <olof@lixom.net>
Cc: Dmitry Torokhov <dtor@chromium.org>
Cc: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Cc: Kever Yang <kever.yang@rock-chips.com>
Cc: Li Zhong <zhong@linux.vnet.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>