iwlwifi: mvm: track changes in beacon count during channel switch

There are some buggy APs that keeps changing the count while forcing
us to block TX. This eventually results in queue hang, assert, and
disconnection. Detect such APs and disconnect gracefully in advance.

Signed-off-by: Sara Sharon <sara.sharon@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>