arm64: defconfig: Enable S2MPS11 clock and S3C RTC driver

The S3C RTC controller on Exynos7 platform uses RTC source clock
from S2MPS11 PMIC. This patch enables the required drivers to make
RTC work on Exynos7 Espresso board.

Signed-off-by: Alim Akhtar <alim.akhtar@samsung.com>
Reviewed-by: Javier Martinez Canillas <javier@osg.samsung.com>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>