arm: Kconfig: Switch XEA (imx287 based) board to use CONFIG_PL01X_SERIAL

The CONFIG_PL011 used by all other ARCH_MX28 based boards is not
supporting DM_SERIAL. Instead, other define - namely CONFIG_PL01X_SERIAL
shall be used by boards supporting DM_SERIAL.

Signed-off-by: Lukasz Majewski <lukma@denx.de>
diff --git a/arch/arm/mach-imx/mxs/Kconfig b/arch/arm/mach-imx/mxs/Kconfig
index 5cffc26..b4a281e 100644
--- a/arch/arm/mach-imx/mxs/Kconfig
+++ b/arch/arm/mach-imx/mxs/Kconfig
@@ -45,6 +45,7 @@
 
 config TARGET_XEA
 	bool "Support XEA"
+	select PL01X_SERIAL
 
 endchoice