qeth: fix possible memory leak in qeth_l3_add_[vipa|rxip]()

ipaddr has been allocated in function qeth_l3_add_vipa() but
does not free before leaving from the error handling cases. The
same problem also exists in function qeth_l3_add_rxip().

spatch with a semantic match is used to found this problem.
(http://coccinelle.lip6.fr/)

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: Frank Blaschka <frank.blaschka@de.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>