ARM: OMAP2+: Add functions to save and restore clockdomain context en-masse.

This is used to support suspend modes like RTC-only and hibernate where
the state of the registers controlling clockdomains is lost.

Signed-off-by: Russ Dill <Russ.Dill@ti.com>
Signed-off-by: Dave Gerlach <d-gerlach@ti.com>
Signed-off-by: Keerthy <j-keerthy@ti.com>
Signed-off-by: Tony Lindgren <tony@atomide.com>