P2P: Fix PBC overlap detection

P2P: Fix PBC overlap detection

PBC overlap detection searches for another BSS with active PBC in the
BSS table. However, when a separate P2P interface is used, scan results
without P2P IE are not saved in the BSS table, so non-P2P BSS's with
active PBC will not be detected.

Fix this by iterating only the WPS AP array instead of the BSS table.
This is also more efficient since only WPS APs may have active PBC. This
also fixes hwsim test "grpform_pbc_overlap" when a dedicated P2P Device
is used.

Signed-off-by: Avraham Stern <avraham.stern@intel.com>