iwlwifi: mvm: Increase the scan timeout guard to 30 seconds

With the introduction of 6GHz channels the scan guard timeout should
be adjusted to account for the following extreme case:

- All 6GHz channels are scanned passively: 58 channels.
- The scan is fragmented with the following parameters: 3 fragments,
  95 TUs suspend time, 44 TUs maximal out of channel time.

The above would result with scan time of more than 24 seconds. Thus,
set the timeout to 30 seconds.

Cc: stable@vger.kernel.org
Signed-off-by: Ilan Peer <ilan.peer@intel.com>
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>
Link: https://lore.kernel.org/r/iwlwifi.20211210090244.3c851b93aef5.I346fa2e1d79220a6770496e773c6f87a2ad9e6c4@changeid
Signed-off-by: Luca Coelho <luciano.coelho@intel.com>