I've found an alternative version of the firmware dvb-demod-si2168-b40-01.fw located here:
http://palosaari.fi/linux/v4l-dvb/firmware/Si2168/Si2168-B40/4.0.25/dvb-demod-si2168-b40-01.fw
But I'm unable to get any information about the two files. Do you know how I can compare the version of the two files. Or get any information about the differences of them?