ASoC: mxs-saif: Fix unused assignment

Delete unused initialized value, because 'ret' will be assigined
by the function of_alias_get_id().

Signed-off-by: Zhang Shengju <zhangshengju@cmss.chinamobile.com>
Signed-off-by: Tang Bin <tangbin@cmss.chinamobile.com>
Link: https://lore.kernel.org/r/20200429093823.1372-1-tangbin@cmss.chinamobile.com


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