Commit 33d915d9 ("{nl,mac}80211: allow 4addr AP operation on
crypto controlled devices") has introduced a change which allows
4addr operation on crypto controlled devices (ex: ath10k). This
change has inadvertently impacted the interface combinations logic
on such devices.

General rule is that software interfaces like AP/VLAN should not be
listed under supported interface combinations and should not be
considered during validation of these combinations; because of the
aforementioned change, AP/VLAN interfaces(if present) will be checked
against interfaces supported by the device and blocks valid interface
combinations.

Consider a case where an AP and AP/VLAN are up and running; when a
second AP device is brought up on the same physical device, this AP
will be checked against the AP/VLAN interface (which will not be
part of supported interface combinations of the device) and blocks
second AP to come up.

Add a new API cfg80211_iftype_allowed() to fix the problem, this
API works for all devices with/without SW crypto control.
Signed-off-by: Manikanta Pubbisetty <mpubbise@codeaurora.org>
Fixes: 33d915d9 ("{nl,mac}80211: allow 4addr AP operation on crypto controlled devices")
Link: https://lore.kernel.org/r/1563779690-9716-1-git-send-email-mpubbise@codeaurora.orgSigned-off-by: Johannes Berg <johannes.berg@intel.com>