wlcore: increase max roc duration to 30 seconds

we don't have any actual limitation in the driver, so
increase it arbitrarily to 30 seconds.

The long ROC is needed for the smart config.flow.

Signed-off-by: Eliad Peller <eliad@wizery.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>