drivers: soc: Add support for Exynos PMU driver

This patch moves Exynos PMU driver implementation from "arm/mach-exynos"
to "drivers/soc/samsung". This driver is mainly used for setting misc
bits of register from PMU IP of Exynos SoC which will be required to
configure before Suspend/Resume. Currently all these settings are done
in "arch/arm/mach-exynos/pmu.c" but moving ahead for ARM64 based SoC
support, there is a need of this PMU driver in driver/* folder.

This driver uses existing DT binding information and there should
be no functionality change in the supported platforms.

Signed-off-by: Amit Daniel Kachhap <amitdanielk@gmail.com>
[tested on Peach-Pi (Exynos5880)]
Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Reviewed-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
[for testing on Trats2 (Exynos4412) and Odroid XU3 (Exynos5422)]
Tested-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
[k.kozlowski: Rebased, add necessary infrastructure for building and
selecting drivers/soc because original patchset was on top of movement
SROMc to drivers/soc]
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
diff --git a/drivers/soc/Makefile b/drivers/soc/Makefile
index 2afdc74..5ade713 100644
--- a/drivers/soc/Makefile
+++ b/drivers/soc/Makefile
@@ -10,6 +10,7 @@
 obj-$(CONFIG_ARCH_MEDIATEK)	+= mediatek/
 obj-$(CONFIG_ARCH_QCOM)		+= qcom/
 obj-$(CONFIG_ARCH_ROCKCHIP)		+= rockchip/
+obj-$(CONFIG_SOC_SAMSUNG)	+= samsung/
 obj-$(CONFIG_ARCH_SUNXI)	+= sunxi/
 obj-$(CONFIG_ARCH_TEGRA)	+= tegra/
 obj-$(CONFIG_SOC_TI)		+= ti/