ASoC: hdmi-codec: remove unused definitions

cppcheck warning:

sound/soc/codecs/hdmi-codec.c:24:16: style: struct member
'hdmi_codec_channel_ma`p_table::map' is never used. [unusedStructMember]
 unsigned char map; /* ALSA API channel map position */
               ^
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Reviewed-by: Bard Liao <yung-chuan.liao@linux.intel.com>
Reviewed-by: Kai Vehmanen <kai.vehmanen@linux.intel.com>
Reviewed-by: Chao Song <chao.song@intel.com>
Link: https://lore.kernel.org/r/20220822184239.169757-2-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>

sound/soc/codecs/hdmi-codec.c

@@ -20,10 +20,6 @@
 
 #define HDMI_CODEC_CHMAP_IDX_UNKNOWN  -1
 
-struct hdmi_codec_channel_map_table {
-	unsigned char map;	/* ALSA API channel map position */
-};
-
 /*
  * CEA speaker placement for HDMI 1.4:
  *