ARM: dts: Set i2c7 clock at 400kHz for exynos based Peach boards

The downstream ChromeOS 3.8 kernel sets the clock frequency
for the I2C bus 7 at 400kHz. Do the same change in mainline.

Suggested-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

arch/arm/boot/dts/exynos5420-peach-pit.dts

@@ -489,6 +489,7 @@
 
 &hsi2c_7 {
 	status = "okay";
+	clock-frequency = <400000>;
 
 	max98090: codec@10 {
 		compatible = "maxim,max98090";