In case of callback based event listener, it is easy for the callback to
filter on the given interface. But in case of the synchronous call it's
not: it would need, after a failed comparison on the interface pointer
to loop by itself on the net_mgmt_event_wait() which is a little bit
heavy (reinstalling the event listener, with the semaphore and all) and
a bit of a burden for the caller itself.
Instead, net_mgmt provides a dedicated call
net_mgmt_event_wait_on_iface() which does it the right way, so the
callback and the related semaphore are destroyed if only the iface
matches the one given as parameter (besides the timeout obviously).
Change-Id: Iab05c3249586f4f4d0447eea42fdac72b8428f2e
Signed-off-by: Tomasz Bursztyka <tomasz.bursztyka@linux.intel.com>