qcacld-3.0: Fix -Wmissing-prototypes in wlan_hdd_tsf

We want to enable the compiler's -Wmissing-prototypes switch, but
there is existing code that is generating warnings. Fix all warnings
in wlan_hdd_tsf.

Change-Id: I37e98814da218d9322a8d3ac05a0e19523859281
CRs-Fixed: 1074336
diff --git a/core/hdd/inc/wlan_hdd_tsf.h b/core/hdd/inc/wlan_hdd_tsf.h
index d53741e..45e2522 100644
--- a/core/hdd/inc/wlan_hdd_tsf.h
+++ b/core/hdd/inc/wlan_hdd_tsf.h
@@ -61,6 +61,7 @@
 };
 
 #ifdef WLAN_FEATURE_TSF
+void wlan_hdd_tsf_init(struct hdd_context_s *hdd_ctx);
 int hdd_capture_tsf(struct hdd_adapter_s *adapter, uint32_t *buf, int len);
 int hdd_indicate_tsf(struct hdd_adapter_s *adapter, uint32_t *buf, int len);
 int wlan_hdd_cfg80211_handle_tsf_cmd(struct wiphy *wiphy,