Older Qualcomm platforms like APQ8016 do not have hardware support for
SoundWire, so kernel configurations made specifically for those platforms
will usually not have CONFIG_SOUNDWIRE enabled.

Unfortunately commit 8d89cf6f ("ASoC: qcom: cleanup and fix
dependency of QCOM_COMMON") breaks those kernel configurations, because
SOUNDWIRE is now a required dependency for SND_SOC_QCOM_COMMON (and in
turn also SND_SOC_APQ8016_SBC). Trying to migrate such a kernel config
silently disables SND_SOC_APQ8016_SBC and breaks audio functionality.

The soundwire helpers in common.c are only used by two of the Qualcomm
audio machine drivers, so building and requiring CONFIG_SOUNDWIRE for
all platforms is unnecessary.

There is no need to stuff all common code into a single module. Fix the
issue by moving the soundwire helpers to a separate SND_SOC_QCOM_SDW
module/option that is selected only by the machine drivers that make
use of them. This also allows reverting the imply/depends changes from
the previous fix because both SM8250 and SC8280XP already depend on
SOUNDWIRE, so the soundwire helpers will be only built if SOUNDWIRE
is really enabled.

Cc: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Fixes: 8d89cf6f ("ASoC: qcom: cleanup and fix dependency of QCOM_COMMON")
Signed-off-by: Stephan Gerhold <stephan@gerhold.net>
Link: https://lore.kernel.org/r/20221231115506.82991-1-stephan@gerhold.netSigned-off-by: Mark Brown <broonie@kernel.org>