qcacld-3.0: Remove wlan_cm_is_sta_connected() prototype

Function wlan_cm_is_sta_connected() was removed by the following patch:
  qcacld-3.0: Code cleanup for connection manager CSR
  Change-Id I156b7ee286f666ee5d660312bf5ba2fe364165c4

However, the prototype was not removed, so remove it now.

Change-Id: Id23f14f1390c72e5f39cef3fbab2eacd6752dc1d
CRs-Fixed: 3430410

components/umac/mlme/connection_mgr/dispatcher/inc/wlan_cm_roam_api.h

@@ -111,14 +111,6 @@ wlan_roam_update_cfg(struct wlan_objmgr_psoc *psoc, uint8_t vdev_id,
  */
 void wlan_cm_send_beacon_miss(uint8_t vdev_id, int32_t rssi);
 
-/**
- * wlan_cm_is_sta_connected() - check if STA is connected
- * @vdev_id: vdev id
- *
- * Return: bool
- */
-bool wlan_cm_is_sta_connected(uint8_t vdev_id);
-
 #else
 static inline
 QDF_STATUS wlan_cm_roam_send_rso_cmd(struct wlan_objmgr_psoc *psoc,