qcacmn: Protect rx execution context for wmi events

wmi rx event context can be modified at runtime by
upper layers. Protect rx execution context for wmi events
to avoid race conditions.

Change-Id: I7eed7108d09f8f39432990b2ebfef29a41bfa9aa
CRs-Fixed: 983619

wmi_unified_priv.h

@@ -621,6 +621,7 @@ struct wmi_unified {
 	struct wmi_ops *ops;
 	void *event_handler_cookie[WMI_UNIFIED_MAX_EVENT];
 	bool use_cookie;
+	qdf_spinlock_t ctx_lock;
 };
 struct wmi_ops *wmi_get_tlv_ops(void);
 struct wmi_ops *wmi_get_non_tlv_ops(void);