ARM: mvebu: switch db-88f6820-amc to DM for i2c

Move existing configuration from header file to defconfig or dts as
appropriate.

Signed-off-by: Chris Packham <judge.packham@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
Reviewed-by: Stefan Roese <sr@denx.de>
diff --git a/arch/arm/dts/armada-385-amc.dts b/arch/arm/dts/armada-385-amc.dts
index a5a8a7f..4649c91 100644
--- a/arch/arm/dts/armada-385-amc.dts
+++ b/arch/arm/dts/armada-385-amc.dts
@@ -54,6 +54,7 @@
 	aliases {
 		ethernet0 = &eth0;
 		ethernet1 = &eth1;
+		i2c0 = &i2c0;
 		spi1 = &spi1;
 	};
 
@@ -68,6 +69,8 @@
 
 		internal-regs {
 			i2c@11000 {
+				clock-frequency = <100000>;
+				u-boot,i2c-slave-addr = <0x0>;
 				pinctrl-names = "default";
 				pinctrl-0 = <&i2c0_pins>;
 				status = "okay";