qeth: layer 3 add missing dev_open/close to ccwgroup handler

In case the ccwgroup device is set online/offline we have to run
the corresponding dev_open/close for the netdevice.

Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>