emac:add set_eth_mac api

components/ethernet/include/esp_eth.h

@@ -250,6 +250,27 @@ static inline esp_err_t esp_eth_smi_wait_set(uint32_t reg_num, uint16_t value_ma
  */
 void esp_eth_free_rx_buf(void *buf);
 
+/**
+ * @brief  Get mac of ethernet interface.
+ *
+ * @param[out] mac: store mac of the interface.
+ *
+ */
+void esp_eth_get_mac(uint8_t mac[6]);
+
+/**
+ * @brief  Set mac of ethernet interface.
+ *
+ * @note user can call this function after emac_init,and the new mac address will be enabled after emac_enable.
+ *
+ * @param[in] mac: the Mac address.
+ *
+ * @return 
+ *    - ESP_OK: succeed
+ *    - ESP_ERR_INVALID_MAC: invalid mac address
+ */
+esp_err_t esp_eth_set_mac(const uint8_t mac[6]);
+
 #ifdef __cplusplus
 }
 #endif