ucm2: codecs: lpass-rx: use set Digital gain at 0dB

ucm2: codecs: lpass-rx: use set Digital gain at 0dB

For some reason we ended up with a Digital gain below 0dB, resulting in
a very low HP volume.
Fix this to 0dB and let Analog gain control HP volume.
Also remove all redundant setting of this control.

Closes: https://github.com/alsa-project/alsa-ucm-conf/pull/335
Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Johan Hovold <johan+linaro@kernel.org>
Tested-by: Johan Hovold <johan+linaro@kernel.org>
Signed-off-by: Jaroslav Kysela <perex@perex.cz>