p2p: do scan to find BSS for group join

If it cannot find BSS in current BSS list, do scan to find BSS
whose SSID matches specified SSID.

Bug: 64695709
Test: CtsVerifier - WiFi Direct
Test: manual test
      * specify frequency for Group Owner.
      * The group is run at specified frequency.
      * specify frequency for Group Client.
      * only specified frequency is scanned

Change-Id: I4bccdd763dee2c33835860fc98e338dbc97a0574
2 files changed