dsp: q6lsm: Check size of payload before access

check size of payload before access in q6lsm_mmapcallback.

Change-Id: I6a755ca4cf54078f0d00f38e303f1b1da29b244c
Signed-off-by: Kumar Anurag Singh <quic_kumaranu@quicinc.com>
(cherry picked from commit bbe748c8dfa4de303462edaba96d4ce283c13bc7)
Signed-off-by: Sandhya Mutha Naga Venkata <quic_smuthana@quicinc.com>