Commit 38279bdb35c1b0c248289752197ebddd2fdd52ef ('D-Bus: Coding style
cleanup') handled the dbus_new_handlers.c change properly, but misplaced
the second 'const' in dbus_old_handlers.c in a way that resulted in
duplicated const rather than marking the actual value const.
Signed-off-by: Jouni Malinen <j@w1.fi>