qeth: Clarify card type naming for virtual NICs

So far, virtual NICs whether attached to a VSWITCH or a guest LAN were always
displayed as guest LANs in the device driver attributes and messages, while
in fact it is a virtual NIC.

Signed-off-by: Stefan Raspl <raspl@linux.vnet.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Reviewed-by: Ursula Braun <ursula.braun@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>