ASoC: msm-lsm-client: Fix possible null pointer dereference

During handling the lsm event, the event status is re-allocated based
on the payload size. Add null check on this allocation to avoid
possible null pointer de-reference.

CRs-fixed: 836640
Change-Id: Id6fb665bd5a73a2fc55d8c5c23b6c72d6101a4cb
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>