ibmvnic: fix to use list_for_each_safe() when delete items

Since we will remove items off the list using list_del() we need
to use a safe version of the list_for_each() macro aptly named
list_for_each_safe().

Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>