RFsim: Allow arbitrary order of beams.

Allow arbitrary order of beam ids in set_beams2 function. This
allows the application to select any arbitrary order of beam ids.
The underlying transport mechanism still uses beam_map so the beam_ids
are ordered before sending.

Also replaced tx_beam_map/rx_beam_map into beam_map.

Also fixed an issue where --rfsimulator.enable_beams required an argument.

radio/COMMON/common_lib.h

@@ -623,6 +623,22 @@ struct openair0_device_t {
    */
   int (*trx_set_beams)(openair0_device *device, uint64_t beam_map, openair0_timestamp timestamp);
 
+    /*! \brief Set tx/rx beams
+   *
+   * Set the tx/rx beams. This has to be done in advance of the reception in order to
+   * allow the underlying device to change receiver configuration. The exact time depends
+   * on the device.
+   *
+   * NOTICE: the samples returned from trx_read_func may belong to more than one beam. It is up
+   * to the application to determine the beam of the received samples.
+   *
+   * \param device the hardware to use
+   * \param beams pointer to array of beam ids
+   * \param num_beams number of beams
+   * \return 0 on success
+   */
+  int (*trx_set_beams2)(openair0_device *device, int* beams, int num_beams, openair0_timestamp timestamp);
+
   /*! \brief RRU Configuration callback
    * \param idx RU index
    * \param arg pointer to capabilities or configuration