qcacmn: Fix KW issue in tdls

Potential NULL pointer dereferences of wmi_handle are found in these
functions:
target_if_tdls_event_handler()
target_if_tdls_register_event_handler()
target_if_tdls_unregister_event_handler()

Do wmi_handle NULL check in the above functions.

Change-Id: I7cb4b574750d6bc6538862aa24a0cf49831b7c25
CRs-Fixed: 2317029
1 file changed