ASoC: soc-pcm: fix the return value in dpcm_apply_symmetry()

ASoC: soc-pcm: fix the return value in dpcm_apply_symmetry()

In case, where the loops are not executed for a reason, the uninitialized
variable 'err' is returned to the caller. Make code fully predictible
and assign zero in the declaration.

Signed-off-by: Jaroslav Kysela <perex@perex.cz>
Cc: Mark Brown <broonie@kernel.org>
Cc: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Link: https://lore.kernel.org/r/20210614071746.1787072-1-perex@perex.cz
Signed-off-by: Mark Brown <broonie@kernel.org>