ARM: SAMSUNG: Consolidate plat/pll.h

Removed
- arch/arm/plat-s3c24xx/include/plat/pll.h
- arch/arm/mach-s3c64xx/include/mach/pll.h
- arch/arm/plat-s5p/include/plat/pll.h
- arch/arm/plat-samsung/include/plat/pll6553x.h

And created
- arch/arm/plat-samsung/include/plat/pll.h

Cc: Ben Dooks <ben-linux@fluff.org>
[kgene.kim@samsung.com: changed title]
[kgene.kim@samsung.com: fixed conflicts in plat-s5p/include/pll.h]
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>