ARM: dts: Use s3c6410-rtc instead of exynos3250-rtc for exynos3250/4415

Mark "samsung,exynos3250-rtc" compatible as deprecated because it
duplicates the "samsung,s3c6410-rtc". Use "samsung,s3c6410-rtc" on
Exynos3250 and Exynos4415 boards.

Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>
Reviewed-by: Chanwoo Choi <cw00.choi@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier.martinez@collabora.co.uk>
Signed-off-by: Kukjin Kim <kgene@kernel.org>