WPS: Fix an interoperability issue with mixed mode and AP Settings

WPS: Fix an interoperability issue with mixed mode and AP Settings

It looks like Windows 7 WPS implementation does not like multiple
Authentication/Encryption Type bits to be set in M7 AP Settings
attributes, i.e., it refused to add a network profile if the AP
was configured for WPA/WPA2 mixed mode and AP PIN was used to
enroll the network.

Leave only a single bit set in the Authentication/Encryption Type
attributes in M7 when the AP is acting as an Enrollee to avoid this
issue.

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