ARM: 7265/1: restart: S3C24XX: use new restart hook

Hook these platforms restart code into the new restart hook rather
than using arch_reset().
And adds local header file, common.h in arch/arm/mach-s3c2410/ and
arch/arm/mach-s3c2440/ directories.

Cc: Ben Dooks <ben-linux@fluff.org>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>
Signed-off-by: Russell King <rmk+kernel@arm.linux.org.uk>