Staging: quatech_usb2: vendor implementation of break_ctl

This patch imports the implementation of the break_ctl, throttle and
unthrottle methods from the vendor driver into the staging driver. This
compiles but is not yet tested.

Signed-off-by: Richard Ash <richard@audacityteam.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>