Fix to return negative error code -ENOMEM from the memory alloc failed
error handling case instead of 0, as done elsewhere in this function.

Fixes: 60e05d1c ("vfio-ccw: add some logging")
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Reviewed-by: Cornelia Huck <cohuck@redhat.com>
Link https://lore.kernel.org/kvm/20190904083315.105600-1-weiyongjun1@huawei.com/Signed-off-by: Christian Borntraeger <borntraeger@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>