soundwire: qcom: wait for fifo space to be available before read/write

If we write registers very fast we can endup in a situation where some
of the writes will be dropped without any notice.

So wait for the fifo space to be available before reading/writing the
soundwire registers.

Signed-off-by: Srinivas Kandagatla <srinivas.kandagatla@linaro.org>
Link: https://lore.kernel.org/r/20210401090058.24041-1-srinivas.kandagatla@linaro.org


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