soundwire: qcom: avoid dependency on CONFIG_SLIMBUS

The driver may be used without slimbus, so don't depend on slimbus.

Signed-off-by: Jonathan Marek <jonathan@marek.ca>
Tested-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Reviewed-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20200905173905.16541-3-jonathan@marek.ca


Signed-off-by: Vinod Koul <vkoul@kernel.org>