cfg80211: support immediate reconnect request hint

There are cases where it's necessary to disconnect, but an
immediate reconnection is desired. Support a hint to userspace
that this is the case, by including a new attribute in the
deauth or disassoc event.

Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20201206145305.58d33941fb9d.I0e7168c205c7949529c8e3b86f3c9b12c01a7017@changeid
Signed-off-by: Johannes Berg <johannes.berg@intel.com>