fbdev: sh_mobile_lcdc: Fix overlay registers update during pan operation

Updating overlay registers require switching to overlay update mode.
This was correctly done when configuring the overlay format and size,
but not when updating the base address registers during pan operation.
Fix it.

Signed-off-by: Laurent Pinchart <laurent.pinchart@ideasonboard.com>

diff --cc drivers/video/sh_mobile_lcdcfb.c
Simple merge