Legacy ioctl() through SIOCDEVPRIVATE are deprecated. Follow the
approach taken by bridge-utils and make use of new bridge ioctl's
whenever possible.
For example, using legacy ioctl() breaks dynamic VLAN mode on 32-bit
Linux systems running 64-bit kernels.
Signed-off-by: Sergey Matyukevich <sergey.matyukevich.os@quantenna.com>