pcie: fix typo in pcie_cap_deverr_init()

Reported-by:
 https://bugs.launchpad.net/qemu/+bug/1393440



Signed-off-by: Gonglei <arei.gonglei@huawei.com>
Reviewed-by: Michael S. Tsirkin <mst@redhat.com>
Signed-off-by: Michael S. Tsirkin <mst@redhat.com>