Clang 6.0.0 complains when initializing structure with { NULL }:

conf/domain_addr.c:1494:38: error: missing field 'type' initializer [-Werror,-Wmissing-field-initializers]
    virDomainDeviceInfo nfo = { NULL };

Use { 0 } instead to make it happy.
Signed-off-by: NRoman Bogorodskiy <bogorodskiy@gmail.com>
Reviewed-by: NMichal Privoznik <mprivozn@redhat.com>