ext3 quota support: fix compile failure

This one was due to a merge error: we added a use of nd.path in commit
2d7c820e ("ext3: add checks for errors
from jbd"), and concurrently we got rid of 'nd' and used a naked 'path'
in commit 8264613d ("[PATCH] switch
quota_on-related stuff to kern_path()").

That all merged cleanly, but it didn't actually _work_.  This should fix
it.

Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>