P2P: Add an option to specify group SSID in P2P_CONNECT join case

P2P: Add an option to specify group SSID in P2P_CONNECT join case

The new optional ssid=<hexdump> argument to P2P_CONNECT can be used to
make P2P Client operations during join-an-existing-group more robust by
filtering out scan results based on the SSID in addition to the P2P
Device/Interface Address. This can help if the same MAC address has been
used in multiple groups recently and the cached scan results may still
include an older BSS.

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