It doesn't appear that the "link status" values in the AP are available in the latest MIB. Is this something that will be included in the future MIB? How about merging the "session status" page and the "link status" page into one?
Have you taken a look at the whispLinkTable in WHISP-AP-MIB (.220.127.116.11.18.104.22.168.3.1.4)? There's a linkSessState OID (.22.214.171.124.126.96.36.199.188.8.131.52.19) that should have the information you're looking for.