Fix for a race where out of order loading of NFS attrs into the
nfsnode could lead to attrs being stale. One example (that we
ran into) was a READDIR+, WRITE. The responses came back in
order, but the attrs from the WRITE were loaded before the
attrs from the READDIR+, leading to the wrong size from being
read on the next stat() call.

MFC after: 1 week
Submitted by: mohans
Approved by: re (kensmith)