ARM: dts: max77686 is exynos5250-snow only

Move it from exynos5250-cros-common.dtsi to exynos5250-snow.dts.
Spring does not need it, it uses an s5m8767 instead.

Signed-off-by: Andreas Faerber <afaerber@suse.de>
Reviewed-by: Doug Anderson <dianders@chromium.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>