config: xea: Enable DM_SERIAL for the XEA (imx287 based) board

The XEA board now supports the DM_SERIAL feature in u-boot.

The SPL is using the SPL_OF_PLATDATA - i.e. NOT SPL_DM_SERIAL to
reduce the overall size of the SPL binary.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
diff --git a/configs/imx28_xea_defconfig b/configs/imx28_xea_defconfig
index 10be4af..c6c6a03 100644
--- a/configs/imx28_xea_defconfig
+++ b/configs/imx28_xea_defconfig
@@ -116,7 +116,8 @@
 CONFIG_DM_REGULATOR=y
 CONFIG_DM_REGULATOR_FIXED=y
 CONFIG_DM_REGULATOR_GPIO=y
-CONFIG_CONS_INDEX=0
+CONFIG_SPECIFY_CONSOLE_INDEX=y
+CONFIG_DM_SERIAL=y
 CONFIG_SPI=y
 CONFIG_DM_SPI=y
 CONFIG_MXS_SPI=y