fteeprom-{erase,prog}: detach logic: change to detach by default As it turns out, detaching all ttyUSB interfaces of a multichannel device does not require outside knowledge of how many channels there are, as in our previous -d option design that is being removed here - instead we can read the bNumInterfaces constant from the USB device's config descriptor and thus know how many interfaces there are in total. Based on this discovery, change the design of fteeprom-{erase,prog} as follows: * remove -d option; * flip the default to where we detach all interfaces by default; * add -n option to NOT detach any interfaces.

# This specimen has been read out from a UB232R module from Digi-Key;
# it is believed to be a genuine FT232RQ chip.

00: 4004 0403 6001 0600 2D80 0008 0200 0A98
10: 0EA2 12B0 0043 0000 030A 0046 0054 0044
20: 0049 030E 0055 0042 0032 0033 0032 0052
30: 0312 0046 0054 0039 004C 0048 0053 004C
40: 0043 0302 0001 0000 0000 0000 0000 0000
50: 0000 0000 0000 0000 0000 0000 0000 0000
60: 0000 0000 0000 0000 0000 0000 0000 0000
70: 0000 0000 0000 0000 0000 0000 0000 95A0