[ARM] 3228/1: SharpSL: Move PM code to arch/arm/common

Patch from Richard Purdie

This patch moves a large chunk of the sharpsl_pm driver to
arch/arm/common so that it can be reused on other devices such as the
SL-5500 (collie). It also abstracts some functions from the core into
the machine and platform specific parts of the driver to aid reuse.

Signed-off-by: Richard Purdie <rpurdie@rpsys.net>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>