ARM: exynos: Remove static mapping of SCU SFR

Lets remove static mapping of SCU SFR mainly used in CORTEX-A9 SoC based
boards. Instead use mapping from device tree node of SCU.

Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Reviewed-by: Alim Akhtar <alim.akhtar@samsung.com>
[mszyprow: rebased, added fallback to scu_a9_get_base() when no SCU DT
 node is available, removed compatibility break warning, fixed non-SMP
 build, keep SCU base mapping to avoid issues with calls from CPUidle]
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Signed-off-by: Krzysztof Kozlowski <krzk@kernel.org>