mx28evk: Convert to CONFIG_DM_SERIAL

The conversion to CONFIG_DM_SERIAL is mandatory, so select this option.

Signed-off-by: Fabio Estevam <festevam@denx.de>
diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 17d69d2..e00c9ee 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -919,7 +919,6 @@
 	bool "NXP i.MX28 family"
 	select CPU_ARM926EJS
 	select GPIO_EXTRA_HEADER
-	select PL011_SERIAL if !TARGET_XEA
 	select MACH_IMX
 	select SUPPORT_SPL
 
diff --git a/arch/arm/mach-imx/mxs/Kconfig b/arch/arm/mach-imx/mxs/Kconfig
index b4a281e..0fd4758 100644
--- a/arch/arm/mach-imx/mxs/Kconfig
+++ b/arch/arm/mach-imx/mxs/Kconfig
@@ -41,6 +41,7 @@
 
 config TARGET_MX28EVK
 	bool "Support mx28evk"
+	select PL01X_SERIAL
 	select BOARD_EARLY_INIT_F
 
 config TARGET_XEA