serial-dmm: rename victor-dmm-ser entry, default to USB HID cable

serial-dmm: rename victor-dmm-ser entry, default to USB HID cable

The serial-dmm entry for Victor DMMs is able to communicate to either
geniune COM ports (RS232 or USB CDC) or the obfuscating USB HID cables.
The victor-dmm driver became obsolete and was removed. Rename the
serial-dmm entry, remove the no longer needed "-ser" suffix. Suggest a
default connection via the obfuscating USB HID cable, accept user
provided overrides for regular serial cables (same behaviour as before,
connection spec for serial ports keeps being mandatory).