imx: mx6ul_14x14_evk select MX6UL

There is no need to expose SoC choice to user, we already got
the SoC according to the build target. So default "select MX6UL"
for MX6UL_14x14_EVK target.

Signed-off-by: Peng Fan <Peng.Fan@freescale.com>
Cc: Stefano Babic <sbabic@denx.de>
Cc: Fabio Estevam <fabio.estevam@freescale.com>

arch/arm/cpu/armv7/mx6/Kconfig

@@ -102,6 +102,7 @@ config TARGET_MX6SXSABRESD
 
 config TARGET_MX6UL_14X14_EVK
 	bool "mx6ul_14x14_evk"
+	select MX6UL
 	select CPU_V7
 	select DM
 	select DM_THERMAL