kea: fix conflict between kea-dhcp6 multilibs

kea: fix conflict between kea-dhcp6 multilibs

There are conflict of config files between kea and lib32-kea:
  | Error: Transaction test error:
  | file /etc/kea/kea-dhcp6.conf conflicts between attempted installs of lib32-kea-2.6.1-r0.core2_32 and kea-2.6.      1-r0.core2_64

Similar to:
  | 8cc65e7eb0 kea: fix conflict between multilibs

Signed-off-by: Lei Maohui <leimaohui@fujitsu.com>
Signed-off-by: Mathieu Dubois-Briand <mathieu.dubois-briand@bootlin.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>