ARM: dts: add async-bridge clocks to gsc power domain for exynos5420

Both GSCALER IPs in gsc power domain have async-bridges (to FIMD and MIXER),
therefore their clocks should be enabled during power domain switch.

Signed-off-by: Andrzej Hajda <a.hajda@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Tested-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Kukjin Kim <kgene@kernel.org>

arch/arm/boot/dts/exynos5420.dtsi

@@ -251,6 +251,8 @@
 		compatible = "samsung,exynos4210-pd";
 		reg = <0x10044000 0x20>;
 		#power-domain-cells = <0>;
+		clocks = <&clock CLK_GSCL0>, <&clock CLK_GSCL1>;
+		clock-names = "asb0", "asb1";
 	};
 
 	isp_pd: power-domain@10044020 {