WPS: Reject station-mode WPS operations when AP mode is enabled

WPS: Reject station-mode WPS operations when AP mode is enabled

Start of station-mode WPS PBC/PIN/Registrar/NFC operation would result
in the AP mode getting disabled. This can be particularly confusing for
the P2P GO case where the group would need to be stopped cleanly. As
such, it is better to reject these invalid operations rather than trying
to handle all corner cases needed to allow this to work robustly.

Signed-off-by: Jouni Malinen <j@w1.fi>