6in4: Corrected tunnelbroker tunnel update URL

Changed the tunnel update URL into format tunnelbrokers
example has, that made it work again. Current method gives "Username/Password
Authentication Failed." when I tried the wget line manually and logread
eventually says also "6in4: update failed". With corrected URL it works fine:
"good 111.222.333.444" or "nochg 111.222.333.444" and logread concurs with
success, and tunnel actually updates.

Tested-by: Vaasa Hacklab <info@vaasa.hacklab.fi>
Signed-off-by: Sami Olmari <sami@olmari.fi>
git-svn-id: svn://svn.openwrt.org/openwrt/trunk@48006 3c298f89-4303-0410-b956-a3cf2f4a3e73