hostapd: Fix dpp_listen in DPP responder scenario

hostapd: Fix dpp_listen in DPP responder scenario

Some time ago it was found some drivers are setting their hw/ucode RX
filters restrictively enough to prevent broadcast DPP Action frames from
being received at upper layers in the stack.

A set of patches was introduced to the kernel and
ath9k driver as well as wpa_supplicant, e.g.,

  a39e9af90 ("nl80211: DPP listen mode callback")
  4d2ec436e ("DPP: Add driver operation for enabling/disabling listen mode")

However, the hostapd code itself was not calling the new multicast
registration. As such the AP side of things wasn't working as expected
in some scenarios. I've found this while trying to get ath9k working as
an AP Responder/Configurator.

The problem wasn't seen on, e.g., mac80211 hwsim driver.

Extend the wpa_supplicant mechanism to work with hostapd as well.

Signed-off-by: Michal Kazior <michal@plume.com>