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/configs/db-88f6820-amc_defconfig b/configs/db-88f6820-amc_defconfig
index e90526a..63fc4db 100644
--- a/configs/db-88f6820-amc_defconfig
+++ b/configs/db-88f6820-amc_defconfig
@@ -36,6 +36,8 @@
 # CONFIG_PARTITION_UUIDS is not set
 # CONFIG_SPL_PARTITION_UUIDS is not set
 CONFIG_SPL_OF_TRANSLATE=y
+CONFIG_DM_I2C=y
+CONFIG_SYS_I2C_MVTWSI=y
 # CONFIG_MMC is not set
 CONFIG_NAND_PXA3XX=y
 CONFIG_SPI_FLASH=y