ASoC: wm_adsp: Improve DSP error handling

If we encounter an error on the DSP side whilst user-space is
waiting on the poll we should call snd_compr_fragment_elapsed,
although data is not actually available we want to wake
user-space such that the error can be propagated out
quickly. Additionally some versions of the DSP firmware are
not super consistent about actually generating an IRQ if they
encounter an error, as such we will check the DSP error status
every time we run out of available data as well, to ensure we
catch it.

Signed-off-by: Charles Keepax <ckeepax@opensource.wolfsonmicro.com>
Signed-off-by: Mark Brown <broonie@kernel.org>