ARM: dts: Add sysreg sytem controller node to exynos5250 and exynos5420

This patch adds sysreg-syscon node to exynos5250 and exynos5420 device
tree, to access System Register's registers using syscon driver.
Signed-off-by: Kamil Debski <k.debski@samsung.com>
[gautam.vivek@samsung.com: Split this syreg-syscon dts entry]
[gautam.vivek@samsung.com: added similar syscon entry for exynos5420]
Signed-off-by: Vivek Gautam <gautam.vivek@samsung.com>
[vikas.sajjan@samsung.com: updated the binding document]
Signed-off-by: Vikas Sajjan <vikas.sajjan@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

Documentation/devicetree/bindings/arm/samsung/sysreg.txt

 SAMSUNG S5P/Exynos SoC series System Registers (SYSREG)
 
 Properties:
- - compatible : should contain "samsung,<chip name>-sysreg", "syscon";
-   For Exynos4 SoC series it should be "samsung,exynos4-sysreg", "syscon";
+ - compatible : should contain two values. First value must be one from following list:
+		- "samsung,exynos4-sysreg" - for Exynos4 based SoCs,
+		- "samsung,exynos5-sysreg" - for Exynos5 based SoCs.
+		second value must be always "syscon".
  - reg : offset and length of the register set.
 
 Example:
@@ -10,3 +12,8 @@ Example:
 		compatible = "samsung,exynos4-sysreg", "syscon";
 		reg = <0x10010000 0x400>;
 	};
+
+	syscon@10050000 {
+		compatible = "samsung,exynos5-sysreg", "syscon";
+		reg = <0x10050000 0x5000>;
+	};

arch/arm/boot/dts/exynos5250.dtsi

@@ -193,6 +193,11 @@ pmu_system_controller: system-controller@10040000 {
 		reg = <0x10040000 0x5000>;
 	};
 
+	sysreg_system_controller: syscon@10050000 {
+		compatible = "samsung,exynos5-sysreg", "syscon";
+		reg = <0x10050000 0x5000>;
+	};
+
 	watchdog@101D0000 {
 		compatible = "samsung,exynos5250-wdt";
 		reg = <0x101D0000 0x100>;

arch/arm/boot/dts/exynos5420.dtsi

@@ -701,6 +701,11 @@ pmu_system_controller: system-controller@10040000 {
 		reg = <0x10040000 0x5000>;
 	};
 
+	sysreg_system_controller: syscon@10050000 {
+		compatible = "samsung,exynos5-sysreg", "syscon";
+		reg = <0x10050000 0x5000>;
+	};
+
 	tmu_cpu0: tmu@10060000 {
 		compatible = "samsung,exynos5420-tmu";
 		reg = <0x10060000 0x100>;