Fix bug where btpan_control_state_callback is called with invalid args.

When there's a connection error, btpan_control_state_callback sometimes
gets called back with incorrect local_role and remote_role values. These
values are simply not set (uninitialized) on one of the error handling
codepaths.

http://b/12854810

Change-Id: Ie2d9d252f185fca48ee6e2bfb697039d0ac10b43