imx6: aristainetos: add DM_SERIAL support

add DM_SERIAL support for the aristainetos board, and
remove not used code from board code.

remove CONSOLE_OVERWRITE_ROUTINE.

Signed-off-by: Heiko Schocher <hs@denx.de>
diff --git a/arch/arm/mach-imx/mx6/Kconfig b/arch/arm/mach-imx/mx6/Kconfig
index c78e919..6bc7405 100644
--- a/arch/arm/mach-imx/mx6/Kconfig
+++ b/arch/arm/mach-imx/mx6/Kconfig
@@ -132,7 +132,9 @@
 	select SYS_I2C_MXC
 	select MXC_UART
 	select FEC_MXC
+	select DM
 	imply CMD_SATA
+	imply CMD_DM
 
 config TARGET_CGTQMX6EVAL
 	bool "cgtqmx6eval"