ASoC: pcm3168a: remove unused ‘format’

In pcm3168a_hw_params(), 'format' is initialized but never used.

sound/soc/codecs/pcm3168a.c: In function ‘pcm3168a_hw_params’:
sound/soc/codecs/pcm3168a.c:405:19: warning: variable ‘format’ set but not
used [-Wunused-but-set-variable]
  snd_pcm_format_t format;

Cc: Damien.Horsley <Damien.Horsley@imgtec.com>
Signed-off-by: Vinod Koul <vinod.koul@intel.com>
Signed-off-by: Mark Brown <broonie@kernel.org>