imx: mx6sabreauto_defconfig: select DM_SERIAL

Select DM_SERIAL

Signed-off-by: Peng Fan <peng.fan@nxp.com>
diff --git a/configs/mx6sabreauto_defconfig b/configs/mx6sabreauto_defconfig
index 8e94a84..639f552 100644
--- a/configs/mx6sabreauto_defconfig
+++ b/configs/mx6sabreauto_defconfig
@@ -98,6 +98,7 @@
 CONFIG_POWER_PFUZE100=y
 CONFIG_DM_REGULATOR=y
 CONFIG_POWER_I2C=y
+CONFIG_DM_SERIAL=y
 CONFIG_MXC_UART=y
 CONFIG_SPI=y
 CONFIG_DM_SPI=y