D-Bus: Fix network block type change

D-Bus: Fix network block type change

It is possible for a network profile to change its type from P2P
persistent group to a normal network and back. The D-Bus interface uses
different types of objects for those, so the object needs to
re-registered in case of type change. This fixes issues in leaving
behind an incorrect type of object and leaking memory when freeing such
a network block that has had its disabled parameter changed.

Signed-off-by: Jouni Malinen <j@w1.fi>