In target_if_tdls_update_fw_state, target_if_tdls_set_offchan_mode,
& target_if_tdls_set_uapsd wmi_handle is derived & dereferenced
with out a NULL check. Add a NULL check for wmi_handle before it is
dereferenced.
Change-Id: If741f69773a712cebcd1be889ca09d01eee97fae
CRs-Fixed: 2305520