ASoC: meson: codec-glue: fix pcm format cast warning

Clarify the cast of snd_pcm_format_t and fix the sparse warning:
restricted snd_pcm_format_t degrades to integer

Fixes: 9c29fd9b ("ASoC: meson: g12a: extract codec-to-codec utils")
Reported-by: kbuild test robot <lkp@intel.com>
Signed-off-by: Jerome Brunet <jbrunet@baylibre.com>
Link: https://lore.kernel.org/r/20200214131350.337968-6-jbrunet@baylibre.com


Signed-off-by: Mark Brown <broonie@kernel.org>