usb: plusb: Add support for National Instruments host-to-host cable

[ Upstream commit 42c972a1f390e3bc51ca1e434b7e28764992067f ]

The National Instruments USB Host-to-Host Cable is based on the Prolific
PL-25A1 chipset.  Add its VID/PID so the plusb driver will recognize it.

Signed-off-by: Ben Shelton <ben.shelton@ni.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>