FT230X Baud Rate Aliasing
Assuming your using the later version for the FTDIPORT.INF file then the answer is to divide 3,000,000 by 125,000 = 24.0 or 18 Hex. So by doing the quick and dirty by looking through the examples of values with no fractional divisors we find.

34,00,00,00 =&gt; divisor = 52, rate = 57,692
1A,00,00,00 =&gt; divisor = 26, rate = 115,384

Change the entry 1A to 18.
Note you have to reload the drivers (reboot is easier in some cases)

Also Note:
The
current ftdiport.inf file contains both formats for the config data string. You select/disable the
correct string by using a ; at the start of the
line to comment out the one you do not want. Only one
entry for Config Data should be used.)