P2P: Add preferred frequency list extension to GO Neg Req

P2P: Add preferred frequency list extension to GO Neg Req

When sending a GO Negotiation Request, advertise the preferred frequency
list in a new vendor specific IE. This can be used to extend the
standard P2P behavior where a single preferred channel can be advertised
by allowing a priority list of channels to be indicated.

Signed-off-by: Jouni Malinen <jouni@qca.qualcomm.com>