usbtmc: add the Siglent VID and reset USB devices in open

usbtmc: add the Siglent VID and reset USB devices in open

Add the Siglent's VID to a list of blacklisted USB TMC devices.
Unconditionally reset USB devices in the open routine.

This was taken from marchel's development for Siglent SDS. Though the
reset should probably be conditional, and only get applied to devices
which are known to need it.

The comment may need adjustment, maybe individual PID entries are
required. The VID probably not only applies to SDS devices, but could
be used for SDG and other gear as well. And lsusb output suggests the
VID is used by Atten, too.