ASoC: omap: Fix the leftover CONFIG_SND_SOC_HDMI_CODEC

Replace the leftover CONFIG_SND_SOC_OMAP_HDMI_CODEC in
sound/soc/omap/Kconfig with CONFIG_SND_SOC_HDMI_CODEC, which was
forgotten in the commit bf7c6e6c.

Signed-off-by: Takashi Iwai <tiwai@suse.de>