ASoC: msm: qdsp6v2: return error when copy from userspace fails

A copy_from_user is not always expected to succeed. Therefore, check
for an error before operating on the buffer post copy.

CRs-Fixed: 1116070
Change-Id: I21032719e6e85f280ca0cda875c84ac8dee8916b
Signed-off-by: Siena Richard <sienar@codeaurora.org>