ASoC: mxs-sgtl5000: Remove unneeded 'ret' variable

Variable 'ret' is not needed here, so just remove it.

Signed-off-by: Fabio Estevam <fabio.estevam@freescale.com>
Acked-by: Shawn Guo <shawn.guo@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>