ARM: dts: imx28-evk: Let i2c0 run at 100kHz

Commit 78b81f4 ("ARM: dts: imx28-evk: Run I2C0 at 400kHz") caused issues
when doing the following sequence in loop:

- Boot the kernel
- Perform audio playback
- Reboot the system via 'reboot' command

In many times the audio card cannot be probed, which causes playback to fail.

After restoring to the original i2c0 frequency of 100kHz there is no such
problem anymore.

This reverts commit 78b81f4.

Cc: <[email protected]> # 3.16+
Signed-off-by: Fabio Estevam <[email protected]>
Signed-off-by: Shawn Guo <[email protected]>

arch/arm/boot/dts/imx28-evk.dts

@@ -193,7 +193,6 @@
 			i2c0: i2c@80058000 {
 				pinctrl-names = "default";
 				pinctrl-0 = <&i2c0_pins_a>;
-				clock-frequency = <400000>;
 				status = "okay";
 
 				sgtl5000: codec@0a {