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 George UberWaves' "FTDI Professional"
# USB-serial cable with OsmocomBB branding; it is believed to be a genuine
# FT232RL chip.

00: 4000 0403 6001 0000 2DA0 0008 0000 0A98
10: 20A2 12C2 1023 0005 030A 0046 0054 0044
20: 0049 0320 0046 0054 0032 0033 0032 0052
30: 0020 0055 0053 0042 0020 0055 0041 0052
40: 0054 0312 0041 0039 0030 0033 0031 0048
50: 0047 0036 B74D 90B9 0000 0000 0000 0000
60: 0000 0000 0000 0000 0000 0000 0000 0000
70: 0000 0000 0000 0000 0000 0000 0000 269F