msm: audio: qdsp6v2: Fix the issue of memory unmap

- Target freeze observed during monkey run.
- Memory unmap getting called from interrupt context,
  which is causing scheduling during atomic operation.
- Avoid calling memory unmap from interrupt context.

Change-Id: Ie05b48ea5b4f919a9050875f30a4615156219213
Signed-off-by: Deepa Madiregama <dmadireg@codeaurora.org>