ARM: S3C24XX: move simtec-specific code to mach directory

This includes a rename of the pm-simtec.c to keep the simtec
extensions together a bit and also better naming of the Kconfig
options.

Signed-off-by: Heiko Stuebner <heiko@sntech.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>