ASoC: ak4642: prevent un-necessary changes to SG_SL1

commit 7b5bfb82882b9b1c8423ce0ed6852ca3762d967a upstream.

If you record the sound during playback,
the playback sound becomes silent.
Modify so that the codec driver does not clear
SG_SL1::DACL bit which is controlled under widget

Signed-off-by: Phil Edworthy <phil.edworthy@renesas.com>
Signed-off-by: Kuninori Morimoto <kuninori.morimoto.gx@renesas.com>
Signed-off-by: Mark Brown <broonie@linaro.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>