[SCTP]: Add the handling of "Set Primary IP Address" parameter to INIT

The ADD-IP "Set Primary IP Address" parameter is allowed in the
INIT/INIT-ACK exchange.  Allow processing of this parameter during
the INIT/INIT-ACK.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>