ASoC: Intel: Skylake: Fix declaration of enum skl_ch_cfg

Constant 'C4_CHANNEL' does not exist on the firmware side. Value 0xC is
reserved for 'C7_1' instead.

Fixes: 04afbbbb

 ("ASoC: Intel: Skylake: Update the topology interface structure")
Signed-off-by: Cezary Rojewski <cezary.rojewski@intel.com>
Signed-off-by: Amadeusz Sławiński <amadeuszx.slawinski@linux.intel.com>
Link: https://lore.kernel.org/r/20230519201711.4073845-4-amadeuszx.slawinski@linux.intel.com
Signed-off-by: Mark Brown <broonie@kernel.org>