There is a post on that on the CFAI website on "How to display status on Linkedin":
http://www.cfainstitute.org/utility/social/Pages/linkedin_status.aspx
You could probably get away with "Charter pending", as that's the status that the CFAI shows on their website for candidates that have passed L3. Though, the CFAI has also specifically stated that even L3 passers may not identify themselves as "Charter pending".
According the CFAI, the phrase we're supposed to use is this awkward one...
"Joe Blow has passed all three levels of the CFA exams and may be eligible for the CFA charter upon completion of the required work experience."