tipc: remove wrong use of NLM_F_MULTI

tipc: remove wrong use of NLM_F_MULTI

NLM_F_MULTI must be used only when a NLMSG_DONE message is sent. In fact,
it is sent only at the end of a dump.

Libraries like libnl will wait forever for NLMSG_DONE.

Fixes: 35b9dd7607f0 ("tipc: add bearer get/dump to new netlink api")
Fixes: 7be57fc69184 ("tipc: add link get/dump to new netlink api")
Fixes: 46f15c6794fb ("tipc: add media get/dump to new netlink api")
CC: Richard Alpe <[email protected]>
CC: Jon Maloy <[email protected]>
CC: Ying Xue <[email protected]>
CC: [email protected]
Signed-off-by: Nicolas Dichtel <[email protected]>
Signed-off-by: David S. Miller <[email protected]>