switch to 5.1 api

Author: paul-szczepanek-arm

features/FEATURE_BLE/targets/TARGET_CORDIO_LL/stack/controller/include/ble/ll_init_api.h

@@ -62,7 +62,7 @@ extern "C" {
 
 #ifndef BT_VER
 /*! \brief  Initialize default BT version. */
-#define BT_VER        LL_VER_BT_CORE_SPEC_5_2
+#define BT_VER        LL_VER_BT_CORE_SPEC_5_1
 #endif
 
 /**************************************************************************************************