Merge branch 'feature/btdm_add_hf_nvrc_command' into 'master'

BT HFP: Add AT+NREC=0 command for disabling AG echo cancellation.

See merge request espressif/esp-idf!5974

components/bt/host/bluedroid/api/include/api/esp_hf_client_api.h

@@ -578,6 +578,20 @@ esp_err_t esp_hf_client_send_dtmf(char code);
  */
 esp_err_t esp_hf_client_request_last_voice_tag_number(void);
 
+/**
+ *
+ * @brief           Disable echo cancellation and noise reduction in the AG (use AT+NREC=0 command)
+ *                  As a precondition to use this API, Service Level Connection shall exist with AG
+ *
+ * @return
+ *                  - ESP_OK: NREC=0 request is sent to lower layer
+ *                  - ESP_INVALID_STATE: if bluetooth stack is not yet enabled
+ *                  - ESP_FAIL: others
+ *
+ */
+esp_err_t esp_hf_client_send_nrec(void);
+
+
 /**
  * @brief           Register HFP client data output function; the callback is only used in
  *                  the case that Voice Over HCI is enabled.