Fix cppcheck warning:

sound/soc/codecs/hdmi-codec.c:745:5: style: Redundant initialization
for 'cf'. The initialized value is overwritten before it is
read. [redundantInitialization]
 cf = dai->playback_dma_data;
    ^
sound/soc/codecs/hdmi-codec.c:738:31: note: cf is initialized
 struct hdmi_codec_daifmt *cf = dai->playback_dma_data;
                              ^
sound/soc/codecs/hdmi-codec.c:745:5: note: cf is overwritten
 cf = dai->playback_dma_data;
    ^
Signed-off-by: Pierre-Louis Bossart <pierre-louis.bossart@linux.intel.com>
Link: https://lore.kernel.org/r/20210312182246.5153-11-pierre-louis.bossart@linux.intel.comSigned-off-by: Mark Brown <broonie@kernel.org>