ASoC: SDCA: Make CONFIG_SND_SOC_SDCA a user selectable symbol

ASoC: SDCA: Make CONFIG_SND_SOC_SDCA a user selectable symbol

Currently, CONFIG_SND_SOC_SDCA is a hidden Kconfig symbol, so it must be
selected by a user selectable symbol to be enabled. However, it may not
be possible for configurations to select this symbol without running
into a recursive dependency issue:

  error: recursive dependency detected!
          symbol SOUNDWIRE depends on SND_SOC_SDCA_OPTIONAL
          symbol SND_SOC_SDCA_OPTIONAL default value contains SND_SOC_SDCA
          symbol SND_SOC_SDCA is selected by SND_SOC_ES9356
          symbol SND_SOC_ES9356 depends on SOUNDWIRE

Turn CONFIG_SND_SOC_SDCA into a user selectable symbol so that drivers
can depend on it and allow the user to enable it explicitly.

Signed-off-by: Nathan Chancellor <nathan@kernel.org>
Link: https://patch.msgid.link/20260526-es9356-dep-fixes-v1-1-39ac16f43d54@kernel.org
Signed-off-by: Mark Brown <broonie@kernel.org>