drivers: wifi: Increase default PS active timeout interval

In crowded environments RPU is active for more than 10s due to too many
retries and this triggers a false RPU recovery. To avoid this, increase
the default to 50s to handle corner cases, as this will only impact the
recovery triggered case, higher timeout doesn't have any impact in
normal cases.

Signed-off-by: Chaitanya Tata <Chaitanya.Tata@nordicsemi.no>