ASoC: dapm: Remove unneeded variable ret returning 0

This patch fixes coccicheck report:
	Unneeded variable: "ret". Return "0" on line 2817

Remove unneccesary variable ret created to return zero.

Signed-off-by: Rajan Vaja <rajan.vaja@gmail.com>
Signed-off-by: Mark Brown <broonie@kernel.org>