fixed ftdi_cbus_func and ftdi_cbush_func enumerations and introduced ftdi_cbusx_func

fixed ftdi_cbus_func and ftdi_cbush_func enumerations and introduced ftdi_cbusx_func

* removed CBUS_BB. D2XX doesn't have it, so I don't think it's actually valid.

* CBUSH_TXLED/CBUSH_RXLED had the wrong values probably because the author
  looked at an outdated D2XX ftdi.h
  These values were also wrong in various mux tables of ftdi.c resulting
  e.g. in confusing outputs of the eeprom.c example.

* ftdi_cbush_func was extended to contain FT230X CBUS functions.
  However, the clock functions are different on FT-X and it is also
  confusing to use CBUSH constants on FT-X chips, so I introduced another
  enum ftdi_cbusx_func with CBUSX constants.

* Added support for setting CBUS functions on FT232H and FT230X in ftdi_eeprom.
  To support these chips, special cbushN and cbusxN options have been
  introduced.
  Possible values of the "cbus" options now match the ftdi.h constant names.
  Libconfuse string lists are no longer used as option types since they do not
  represent enumerations but lists.

* When "cbus" options are missing in ftdi_eeprom config files, keep the
  chip defaults as set by ftdi_eeprom_initdefaults().