1. While parsing flags, it overrides mode.
2. Before, dump-line and dump-details are same leading that macvlan info will be shown twice while dumpping details.
So make dump-line show nothing.
3. Add some spaces to show dump-details more prettier.
Signed-off-by: Wang Jian <jianjian.wang1@gmail.com> Fixes: c76393e2037d78eb60c32f95b26f5b1e5b9422a6
http://lists.infradead.org/pipermail/libnl/2018-August/002405.html
http://lists.infradead.org/pipermail/libnl/2018-September/002406.html
http://lists.infradead.org/pipermail/libnl/2018-September/002411.html