ARM: 7247/1: S5PC100: introduce arch/arm/mach-s5pc100/common.[ch]

This patch introduces common.[ch] which are used only in the
arch/arm/mach-s5pc100/ directory. The common.c file merges
the cpu.c and init.c which are used commonly on S5PC100 SoC
and the common.h local header file replaces with plat/s5pc100.h
file.

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>