BACKPORT: mac80211_hwsim: add concurrent channels scanning support over virtio

This fixed the crash when setting channels to 2 or more when
communicating over virtio.

Signed-off-by: Weilun Du <wdu@google.com>
Link: https://lore.kernel.org/r/20210506180530.3418576-1-wdu@google.com


Signed-off-by: Johannes Berg <johannes.berg@intel.com>

(cherry picked from commit 626c30f9e77354301ff9162c3bdddaf92d9b5cf3 https://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next.git/commit/?id=626c30f9e77354301ff9162c3bdddaf92d9b5cf3

)
Bug: 182576217
Signed-off-by: Weilun Du <wdu@google.com>
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Ia9be6c1d962b941a92f4e1be41e874dbe08024e5
(cherry picked from commit d1e50a709c169e3f090c8bdd23f86547b82b5d55)