VPN: increase timeout period to 60 seconds for legacy VPN.

Some VPN needs more time than others in order to create the secure tunnel.
For example, L2TP/IPSec PSK on average needs 15 seconds on WiFi. On mobile
connection, variation gets larger, and it sometimes needs more than 30
seconds. This change increases timeout period from 30 to 60 seconds.

Change-Id: I6006fd254a7bc91c22f63d2f3f20ea79ee9b05e2