ASoC: imx-audmux: remove unnecessary check of clk_disable_unprepare/clk_prepare_enable

ASoC: imx-audmux: remove unnecessary check of clk_disable_unprepare/clk_prepare_enable

Because clk_disable_unprepare/clk_prepare_enable already checked NULL clock
parameter, so the additional checks are unnecessary, just remove them.

Reported-by: Zeal Robot <zealci@zte.com.cn>
Signed-off-by: Minghao Chi <chi.minghao@zte.com.cn>
Acked-by: Shengjiu Wang <shengjiu.wang@gmail.com>
Link: https://lore.kernel.org/r/20220606033705.291048-1-chi.minghao@zte.com.cn
Signed-off-by: Mark Brown <broonie@kernel.org>