package/hostapd: enable Linux ioctls for VLANs

Hostapd v2.9 follows the approach taken by bridge-utils and attempts
to use new bridge ioctls whenever possible. New bridge calls are
enabled in hostapd build using NEED_LINUX_IOCTL configuration option.
That switch is enabled for all the practical configurations excluding
wired driver. However it is required to support dynamic VLANs in
any configuration.

Enable NEED_LINUX_IOCTL hostapd configuration option whenever
dynamic VLANs support is requested in buildroot.

Fixes:
http://autobuild.buildroot.net/results/71a/71aa92578622a266b4bed92b66a65438bc32cbd6



Signed-off-by: Sergey Matyukevich <geomatsi@gmail.com>
Signed-off-by: Arnout Vandecappelle (Essensium/Mind) <arnout@mind.be>