ASoC: msm: qdsp6v2: Ignore unexpected events from dsp

If dsp responds with an unexpected event, audio driver
should ignore the response and continue. Change removes
the BUG_ON and handles error gracefully.

Change-Id: Ie7bbf1ea9b47630dae38e89887e53883f8f1dc12
CRs-fixed: 512784
Signed-off-by: Gopikrishnaiah Anandan <agopik@codeaurora.org>