video: sh_mobile_lcdcfb suspend/resume support

This patch adds suspend/resume support to the LCDC
driver for SuperH Mobile - sh_mobile_lcdcfb.

We simply stop hardware on suspend and start it again
on resume. For RGB panels this is trivial, but for SYS
panels in deferred io mode this becomes a bit more
difficult - we need to wait for a frame end interrupt
to make sure the clocks are balanced before stopping
the actual hardware.

Signed-off-by: Magnus Damm <damm@igel.co.jp>
Signed-off-by: Paul Mundt <lethal@linux-sh.org>