[connman] AutoConnect to old service when connection to new service fails

[connman] AutoConnect to old service when connection to new service fails

In the following scenario:
1. Device is connected to AP1.
2. Connection requested initiated with AP2.

AP1 gets disconnected and device initiates connection with AP2. If
connection with AP2 fails(like invalid key, dhcp-failed error) then
device should auto connect to AP1.
This patch initiates auto connect to last connected AP's

Change-Id: Iad5c4cf50da7a91869994abc133b24d66c99b0bc
Signed-off-by: Saurav Babu <saurav.babu@samsung.com>