MAINTAINERS: Add maintainers entry for drivers/soc/samsung

This patch adds maintainers entry for new driver folder
drivers/soc/samsung

Signed-off-by: Pankaj Dubey <pankaj.dubey@samsung.com>
Signed-off-by: Kukjin Kim <kgene@kernel.org>
Signed-off-by: Krzysztof Kozlowski <k.kozlowski@samsung.com>