ASoC: msm-cpe-lsm: Validate the payload size before allocation

The payload size for keyword detection event status is received from
userspace through IOCTL. This payload size is used to allocate memory in
the driver. Validate the payload size before memory allocation to make
sure the payload size is within the maximum allowed size.

CRs-fixed: 842343
Change-Id: I975201e79ab4b111a1b2aad0be6aa65fdec71dcc
Signed-off-by: Bhalchandra Gajare <gajare@codeaurora.org>