lock/unlock mismatch in ttm_bo.c

[Tom St Denis]

Hi all,

In the function ttm_bo_cleanup_refs() it seems possible to get to line 
551 without entering the block on 516 which means you'll be unlocking a 
mutex that wasn't locked.

Now it might be that in the course of the API this pattern cannot be 
expressed but it's not clear from the function alone that that is the case.

Thoughts?

Tom