ASoC: fsl_audmux: Fix amixer write errors

ASoC: fsl_audmux: Fix amixer write errors

This reverts commit 3bca7098c9565a ("ASoC: fsl_audmix: make clock and
output src write only").

There is error after making clock and output src write only

$amixer -c imxaudmix cset numid=1 1
amixer: Cannot read the given element from control sysdefault:3

Which is worse than before, so let's revert the change.

Signed-off-by: Shengjiu Wang <shengjiu.wang@nxp.com>
Link: https://lore.kernel.org/r/1662446961-20799-1-git-send-email-shengjiu.wang@nxp.com
Signed-off-by: Mark Brown <broonie@kernel.org>