MAINTAINERS: Add linux-samsung-soc mailing list for Samsung

There's a Samsung-specific mailing list but it's not advertised in
MAINTAINERS - add it to the overall architecture to make it more
discoverable.

Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
[kgene.kim@samsung.com: added notice of 'moderated']
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>

MAINTAINERS

@@ -1054,6 +1054,7 @@ ARM/SAMSUNG ARM ARCHITECTURES
 M:	Ben Dooks <ben-linux@fluff.org>
 M:	Kukjin Kim <kgene.kim@samsung.com>
 L:	linux-arm-kernel@lists.infradead.org (moderated for non-subscribers)
+L:	linux-samsung-soc@vger.kernel.org (moderated for non-subscribers)
 W:	http://www.fluff.org/ben/linux/
 S:	Maintained
 F:	arch/arm/plat-samsung/