include/video: move fimd register headers from platform to include/video

This patch moves the contents from regs-fb-v4.h and regs-fb.h to
include/video/samsung_fimd.h. Also updates the header inclusion in
machine files and driver files accordingly.

Signed-off-by: Leela Krishna Amudala <l.krishna@samsung.com>
Cc: Florian Tobias Schandinat <FlorianSchandinat@gmx.de>
Signed-off-by: Kukjin Kim <kgene.kim@samsung.com>