ASoC: OMAP: HDMI: Make sound card naming more generic

Rename all the relevant structures, variables and functions to not
make specific reference to OMAP4. This is to make the driver encompass
future OMAP versions that feature HDMI and not only OMAP4. These
changes are only in naming. There are not functional changes.

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>