[PATCH 9/9] s390: qeth driver fixes [6/6]

From: Frank Pavlic <fpavlic@de.ibm.com>
	- Hipersockets has no IPV6 support, thus prevent issueing
	  SETRTG_IPV6 control commands on Hipersockets devices.
	- fixed error handling in qeth_sysfs_(un)register

Signed-off-by: Frank Pavlic <fpavlic@de.ibm.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>