dsp: afe: call get params with afe cmd lock held

If get params is called without afe cmd lock, it
leads to race conditions with other callers calling
afe_apr_send_pkt and the status values read back
are getting overwritten wrongly by the callers that
call without lock.

Change-Id: I5af4d7bbbe01357dd9b6ae8efbe1831401003508
Signed-off-by: Karthikeyan Mani <kmani@codeaurora.org>