dsp_ready_completion is redundant and can be replaced by a call
flush_work() to wait for cs35l56_dsp_work() to complete.

As the dsp_work is queued by component_probe() it must run before other
ASoC component callbacks and therefore there is no risk of calling
flush_work() before the dsp_work() has been queued.
Signed-off-by: Simon Trimmer <simont@opensource.cirrus.com>
Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/20230414133753.653139-5-rf@opensource.cirrus.comSigned-off-by: Mark Brown <broonie@kernel.org>