ipv6: support IFA_F_MANAGETEMPADDR for address deletion too

Userspace applications can use IFA_F_MANAGETEMPADDR with RTM_NEWADDR
already to indicate that the kernel should take care of temporary
address management.

This patch adds related functionality to RTM_DELADDR. By setting
IFA_F_MANAGETEMPADDR a userspace application can indicate that the kernel
should delete all related temporary addresses as well.

A corresponding patch for the "ip addr del" command has been applied to
iproute2 already.

Signed-off-by: Heiner Kallweit <heiner.kallweit@web.de>
Reviewed-by: Jiri Pirko <jiri@resnulli.us>
Acked-by: Hannes Frederic Sowa <hannes@stressinduktion.org>
Signed-off-by: David S. Miller <davem@davemloft.net>