exynos: Add support for spring

Spring is the first ARM-based HP Chromebook 11. It is similar to snow
and it uses the same Samsung Exynos5250 chip. But has some unusual
features. Mainline support for it has lagged snow (both in kernel and
U-Boot). Now that the exynos5 code is common we can support spring just
by adding a device tree and a few lines of configuration.

Signed-off-by: Simon Glass <sjg@chromium.org>

arch/arm/cpu/armv7/exynos/Kconfig

@@ -51,6 +51,12 @@ config TARGET_SNOW
 	select OF_CONTROL
 	select SPL_DISABLE_OF_CONTROL
 
+config TARGET_SPRING
+	bool "Spring board"
+	select SUPPORT_SPL
+	select OF_CONTROL
+	select SPL_DISABLE_OF_CONTROL
+
 config TARGET_SMDK5420
 	bool "SMDK5420 board"
 	select SUPPORT_SPL