This patch enables DM I2C for DHCOM i.MX6 PDK2 boards and
removes non DM I2C code. The I2C EEPROM with ethaddr (MAC)
is defined in the device tree. Use UCLASS_I2C_EEPROM
to find the device by fixed hardware path and read the ethaddr.

Tested with DHCOM i.MX6dl and DHCOM i.MX6q.
Signed-off-by: NLudwig Zenz <lzenz@dh-electronics.com>
Reviewed-by: NMarek Vasut <marex@denx.de>