msm:qdsp6v2: Check null pointer on userspace data argument in kernel

The null pointer check is required to ensure that userspace data
in kernalspace is not null.

Change-Id: I9e522c393ae643626a4bae03731a73f5d6db6458
CRs-Fixed: 563752
Signed-off-by: Mohammad Johny Shaik <mjshai@codeaurora.org>