ARM: S3C64XX: Cleanup mach/regs-fb.h from mach-s3c64xx

Use plat/regs-fb-v4.h in machine files instead of mach/regs-fb.h.

Signed-off-by: Ajay Kumar <ajaykumar.rs@samsung.com>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>