video: sh_mobile_lcdcfb: Support HAVE_CLK=n configurations.

This provides a workaround for users of sh_mobile_lcdcfb that don't
define HAVE_CLK and have otherwise sane clock initialization.

At the same time, move the sh_mobile_lcdc.h header to include/video/.

Signed-off-by: Paul Mundt <lethal@linux-sh.org>