ARM: exynos: Add CPU state management for Exynos542x under secure firmware

Add required CPU state management done via secure monitor call for
Exynos542x running unsed Secure Firmware.

Signed-off-by: Joonyoung Shim <jy0922.shim@samsung.com>
[mszyprow: rewrote code to use defines and sysram base address instead
 of the magic numbers, added second smc call in pm_resume, rephrased
 subject and commit message]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>