ARM: SMDK6410: Add Watchdog support for SMDK6410

This patch adds support for Watchdog timer for Samsung S3C6410

Signed-off-by: Banajit Goswami <banajit.g@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Ben Dooks <ben-linux@fluff.org>