ANDROID: GKI: cfg80211: Add AP stopped interface

AP stopped interface can be used to indicate that the AP mode has
stopped functioning, WLAN driver may have encountered errors that has
forced the driver to stop the AP mode.

When the driver is in P2P-Go mode, and when it goes thru automatic
recovery from firmware crashes, it uses this interface to notify the
userspace that the group has been deleted.

CRs-Fixed: 1078172
Bug: 150894598
Test: make
Signed-off-by: Sameer Thalappil <sameert@codeaurora.org>
Change-Id: Id566b35cd0afdb7277fbd2aef74601bfabc65e42
(cherry picked from commit 44643035)
Signed-off-by: Hridya Valsaraju <hridya@google.com>