net: Add USB PID for new MOSCHIP USB ethernet controller MCS7832 variant

Due to active notification of the new MCS7832 version by the manufacturer
(Mr. Milton; thanks!) -- quote: "functionality same as MCS7830",
I'm now submitting this patch (on -rc6), intended for networking.git and -stable.

- add MCS7832 USB PID to be able to support this new device variant, too
- add related descriptions

Signed-off-by: Andreas Mohr <andi@lisas.de>
Signed-off-by: David S. Miller <davem@davemloft.net>