sctp: allocate sctp_sockaddr_entry with kzalloc

The similar issue as fixed in Commit 4a2eb0c3

 ("sctp: initialize
sin6_flowinfo for ipv6 addrs in sctp_inet6addr_event") also exists
in sctp_inetaddr_event, as Alexander noticed.

To fix it, allocate sctp_sockaddr_entry with kzalloc for both sctp
ipv4 and ipv6 addresses, as does in sctp_v4/6_copy_addrlist().

Reported-by: Alexander Potapenko <glider@google.com>
Signed-off-by: Xin Long <lucien.xin@gmail.com>
Reported-by:  <syzbot+ae0c70c0c2d40c51bb92@syzkaller.appspotmail.com>
Acked-by: Marcelo Ricardo Leitner <marcelo.leitner@gmail.com>
Acked-by: Neil Horman <nhorman@tuxdriver.com>
Signed-off-by: David S. Miller <davem@davemloft.net>