BTM_BleEnhancedTransmitterTest() function

* Function BTM_BleEnhancedTransmitterTest * Description This function is called to start the LE Enhanced Transmitter test * Parameter tx_freq - Frequency Range * test_data_len - Length in bytes of payload data in each packet * packet_payload - Pattern to use in the payload * phy - The type of phy that sends data * p_cmd_cmpl_cback - Command Complete callback