video: sh_mobile_lcdcfb: use both register sets for display panning

Switch to using both register sets - side A and side B for display panning.

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>