net: sctp: fix initialization of local source address on accepted ipv6 sockets

commit 	efe4208f:
'ipv6: make lookups simpler and faster' broke initialization of local source
address on accepted ipv6 sockets. Before the mentioned commit receive address
was copied along with the contents of ipv6_pinfo in sctp_v6_create_accept_sk.
Now when it is moved, it has to be copied separately.

This also fixes lksctp's ipv6 regression in a sense that test_getname_v6, TC5 -
'getsockname on a connected server socket' now passes.

Signed-off-by: Matija Glavinic Pecotic <matija.glavinic-pecotic.ext@nsn.com>
Signed-off-by: David S. Miller <davem@davemloft.net>