cfg: Update Flyswatter 2 URL

It pointed to the Flyswatter 1 page.

Change-Id: Ib7e82669a31cad2bf8f6ba4a60b25ef9920b2584
Signed-off-by: Andreas Fritiofson <andreas.fritiofson@gmail.com>
Reviewed-on: http://openocd.zylin.com/1478
Tested-by: jenkins
Reviewed-by: Xiaofan <xiaofanc@gmail.com>
Reviewed-by: Spencer Oliver <spen@spen-soft.co.uk>