ASoC: cs35l56: Remove quick-cancelling of dsp_work()

Delete the 'removing' flag and don't kick init_completion to make a
quick cancel of dsp_work(). Just let it timeout on the wait for the
completion.

Simplify the code to standard cancelling or flushing of the work.
This avoids introducing corner cases from a layer of custom signalling.
It also avoids potential race conditions when system-suspend handling
is added.

Unless the hardware is broken, the dsp_work() will already have started
and passed the completion before the driver would want to cancel it.

Signed-off-by: Richard Fitzgerald <rf@opensource.cirrus.com>
Link: https://lore.kernel.org/r/168122674746.26.16881587647873355224@mailman-core.alsa-project.org
Signed-off-by: Mark Brown <broonie@kernel.org>