WPS: Send the credential when learning AP params in registrar role

WPS: Send the credential when learning AP params in registrar role

When the supplicant acts as a registrar to learn the access point
parameters send the credentials to the wpa_cli interface after
receiving the 7th message. This is needed for proper behavior with
wps_cred_processing set to 1 or 2.

Without this patch, after the 7th message you got the WPS-CRED-RECEIVED
notification without the credentials. This was because the cred_attr and
cred_attr_len were not filled in in the wps structure.

Signed-off-by: Olivier Sobrie <olivier@sobrie.be>