ASoC: OMAP: HDMI: Rename sound card source file

Rename sound card driver source file to encompass not only OMAP4 but future
OMAP versions that feature HDMI.

Signed-off-by: Ricardo Neri <ricardo.neri@ti.com>
Acked-by: Mark Brown <broonie@opensource.wolfsonmicro.com>
Signed-off-by: Liam Girdwood <lrg@ti.com>