ASoC: codecs: tx-macro: fix kcontrol put

tx_macro_tx_mixer_put() and tx_macro_dec_mode_put() currently returns zero
eventhough it changes the value.
Fix this, so that change notifications are sent correctly.

Fixes: d207bdea

 ("ASoC: codecs: lpass-tx-macro: add dapm widgets and route")
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20220906170112.1984-6-srinivas.kandagatla@linaro.org
Signed-off-by: Mark Brown <broonie@kernel.org>