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.

Bug: 35399404
Change-Id: Ibba9a47c84e735d30e32eeac5b80d51044b7a9e8
CRs-Fixed: 1094852
Signed-off-by: Siena Richard <sienar@codeaurora.org>