ARM: mxs: add initial device tree support for imx23-evk board

It adds initial device tree support for imx23-evk board, and only
serial console is enabled.

Signed-off-by: Shawn Guo <shawn.guo@linaro.org>
Acked-by: Marek Vasut <marex@denx.de>
diff --git a/arch/arm/mach-mxs/Kconfig b/arch/arm/mach-mxs/Kconfig
index 15bb4e2..8138a13 100644
--- a/arch/arm/mach-mxs/Kconfig
+++ b/arch/arm/mach-mxs/Kconfig
@@ -23,6 +23,7 @@
 
 config MACH_MXS_DT
 	bool "Support MXS platforms from device tree"
+	select SOC_IMX23
 	select SOC_IMX28
 	select USE_OF
 	help