macvtap: fix uninitialized return value macvtap_ioctl_set_queue()

Return -EINVAL on illegal flag instead of uninitialized value. This fixes the
kbuild test warning.

Signed-off-by: Jason Wang <jasowang@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
1 file changed