ASoC: msm: Check the pointers before memcpy

Check the pointers before memcpy when the application queries
the adsp capability for compressed audio. Invalid pointer
can cause kernel panic when doing memcpy.

CRs-fixed: 665297
Change-Id: I522deffc42f792b8dfdcf50272a80cd0d1e5a9ee
Signed-off-by: Kuirong Wang <kuirongw@codeaurora.org>