qeth: HiperSockets layer-3 interface drop non IPv4 or non IPv6 packets

HiperSockets infrastructure (layer-3 mode) supports only IPv4 or
IPv6 packets. Sending other packet types disturbs TCP/IP on z/VM,
which issues messages about invalid packets.
Qeth send routine will detect packet type on sending over a
HiperSockets interface (in layer-3 mode) and drop non IP packets.
The error and drop count of the interface is incremented.

Signed-off-by: Klaus D. Wacker <kdwacker@de.ibm.com>
Signed-off-by: Ursula Braun <braunu@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>