dsp: q6lsm: revert Check size of payload before access

check size of payload before access in q6lsm_mmapcallback.

The payload size can be either 4 or 8 bytes.
Code to verify the payload size is atleast 4 bytes is added.

Change-Id: Ibfc19c0ff2de3234d2786470a6f5e48a5fef04b4
Signed-off-by: Shaik Jabida <quic_sjabida@quicinc.com>