drm/msm/dp: Use function arguments for audio operations

drm/msm/dp: Use function arguments for audio operations

The dp_audio read and write operations uses members in struct dp_catalog
for passing arguments and return values. This adds unnecessary
complexity to the implementation, as it turns out after detangling the
logic that no state is actually held in these variables.

Clean this up by using function arguments and return values for passing
the data.

Reviewed-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>
Signed-off-by: Bjorn Andersson <quic_bjorande@quicinc.com>
Patchwork: https://patchwork.freedesktop.org/patch/585350/
Link: https://lore.kernel.org/r/20240328-msm-dp-cleanup-v2-6-a5aed9798d32@quicinc.com
Signed-off-by: Dmitry Baryshkov <dmitry.baryshkov@linaro.org>