fbdev: sh_mobile_hdmi: fix compilation without SOUND enabled

At least two more Kconfig options have to be selected to be able to compile
sh_mobile_hdmi.

Signed-off-by: Guennadi Liakhovetski <g.liakhovetski@gmx.de>
Acked-by: Liam Girdwood <lrg@slimlogic.co.uk>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>