P2P: Require fresh scan results for persistent group re-invocation

P2P: Require fresh scan results for persistent group re-invocation

The P2P group is not yet operating when going through invitation
exchange for re-invocation. Previously, an old cached scan result could
be used to skip the scan immediately after the invitation exchange.
While this may result in the fastest possible connection, it does have
some issues with cases where the GO takes some time to start up. It
would also be at least theoretically possible for some of the BSS
parameters to be different, so having a fresh scan result from the new
GO instance may be desired in any case.

Add a mechanism to skip scan results that have been last updated before
a specific point in time and as the first user for this mechanism,
require chan results to be more recent than the invitation message
exchange for the P2P Client role in persistent group re-invocation case.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>