NimBLE: Make LE data length set API public

- Helps to set LE data length in controller from host.

nimble/host/include/host/ble_gap.h

@@ -1139,6 +1139,23 @@ int ble_gap_adv_set_fields(const struct ble_hs_adv_fields *rsp_fields);
  */
 int ble_gap_adv_rsp_set_fields(const struct ble_hs_adv_fields *rsp_fields);
 
+/**
+ * Configure LE Data Length in controller (OGF = 0x08, OCF = 0x0022).
+ *
+ * @param conn_handle      Connection handle.
+ * @param tx_octets        The preferred value of payload octets that the Controller
+ *                         should use for a new connection (Range
+ *                         0x001B-0x00FB).
+ * @param tx_time          The preferred maximum number of microseconds that the local Controller
+ *                         should use to transmit a single link layer packet
+ *                         (Range 0x0148-0x4290).
+ *
+ * @return              0 on success,
+ *                      other error code on failure.
+ */
+int ble_hs_hci_util_set_data_len(uint16_t conn_handle, uint16_t tx_octets,
+                                 uint16_t tx_time);
+
 #if MYNEWT_VAL(BLE_EXT_ADV)
 /** @brief Extended advertising parameters  */
 struct ble_gap_ext_adv_params {

nimble/host/src/ble_hs_hci_priv.h

@@ -100,8 +100,6 @@ int ble_hs_hci_util_read_adv_tx_pwr(int8_t *out_pwr);
 int ble_hs_hci_util_rand(void *dst, int len);
 int ble_hs_hci_util_read_rssi(uint16_t conn_handle, int8_t *out_rssi);
 int ble_hs_hci_util_set_random_addr(const uint8_t *addr);
-int ble_hs_hci_util_set_data_len(uint16_t conn_handle, uint16_t tx_octets,
-                                 uint16_t tx_time);
 int ble_hs_hci_util_data_hdr_strip(struct os_mbuf *om,
                                    struct hci_data_hdr *out_hdr);
 int ble_hs_hci_evt_process(const struct ble_hci_ev *ev);