ARM: dts: convert to generic power domain bindings for exynos DT

This patch replaces all custom samsung,power-domain dt
properties with generic power domain bindings and updates
documentation Samsung's devices referring to old binding.

Suggested-by: Kevin Hilman <khilman@kernel.org>
Signed-off-by: Marek Szyprowski <m.szyprowski@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
[javier.martinez@collabora.co.uk: tested on the Exynos5800 Peach Pi Chromebook]
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Kukjin Kim <kgene@kernel.org>
diff --git a/arch/arm/boot/dts/exynos4210.dtsi b/arch/arm/boot/dts/exynos4210.dtsi
index bcc9e63..6728aaa 100644
--- a/arch/arm/boot/dts/exynos4210.dtsi
+++ b/arch/arm/boot/dts/exynos4210.dtsi
@@ -79,6 +79,7 @@
 	pd_lcd1: lcd1-power-domain@10023CA0 {
 		compatible = "samsung,exynos4210-pd";
 		reg = <0x10023CA0 0x20>;
+		#power-domain-cells = <0>;
 	};
 
 	gic: interrupt-controller@10490000 {