ASoC: max98090: Remove unnecessary braces

Braces are not required for single line statements.
Silences the following checkpatch warnings:
WARNING: braces {} are not necessary for single statement blocks.

Signed-off-by: Sachin Kamat <sachin.kamat@linaro.org>
Signed-off-by: Mark Brown <broonie@opensource.wolfsonmicro.com>