qcacld-3.0: Avoid NULL pointer dereference in lim_send_auth_mgmt_frame

pLimJoinReq will be NULL for the pe session, created when
STA does a successful FT-Preauth with target AP, using LFR
2.0 based roaming.
Any subsequent roaming using this new pe session will cause NULL
pointer dereference.
Hence checking validity of session->pLimJoinReq before accessing.

Change-Id: I47480a4d22c02ce1cc804430f60e8adf7959164e
CRs-Fixed: 2433647
1 file changed