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 <[e-mail]>
Signed-off-by: Kukjin Kim <[e-mail]>
Signed-off-by: Krzysztof Kozlowski <[e-mail]>

MAINTAINERS

···
 F:	arch/arm/mach-exynos*/
 F:	drivers/*/*s3c2410*
 F:	drivers/*/*/*s3c2410*
+F:	drivers/soc/samsung/*
 F:	drivers/spi/spi-s3c*
 F:	sound/soc/samsung/*
 F:	Documentation/arm/Samsung/