ASoC: fsl_sai: Keep symmetry for clk_enable() and clk_disable()

There are two functions haven't clk_disable_unprepare() if having error.
Thus fix them.

Signed-off-by: Nicolin Chen <Guangyu.Chen@freescale.com>
Reviewed-by: Xiubo Li <Li.Xiubo@freescale.com>
Signed-off-by: Mark Brown <broonie@linaro.org>