qeth: Add new s390 debug feature for each qeth card

This patch adds a debug area for each qeth card. This debug area will replace
various other debug areas that are global for all cards handled by the device
driver. On crash dump analysis this makes life easier when trying to find out
what's going on with an interface. Also, the forest of debug areas for this
device driver is significantly cleared up.

Signed-off-by: Carsten Otte <cotte@de.ibm.com>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>