qcacld-3.0: Fix null session dereference in lim_populate_he_mcs_set

Currently, ch_width of session is checked without validating
session  which may lead to NULL pointer derefrence.

validate session_entry before accessing element of
pe_session

Change-Id: I1f785555fa77a0c588e9b5245ad513fe059974d0
CRs-Fixed: 2585928
1 file changed