auto_init: remove destiny init

This handler does not fulfill its purpose to initialize the destiny
module correctly. E.g. 'examples/rpl_udp' needs to initialize some
modules in the beginning and then initialize destiny.

Fix: 'examples/rpl_udp' is currently *double* initializing destiny.
See: https://github.com/RIOT-OS/RIOT/blob/master/examples/rpl_udp/rpl.c#L93