Fix cherry-pick of “Linux: 2.6.38: dentry->d_count is not an atomic”

Fix cherry-pick of “Linux: 2.6.38: dentry->d_count is not an atomic”

Gerrit broke this patch while cherry-picking it; see
http://gerrit.openafs.org/3999 .

Change-Id: I16c8263d4173af35e524f0ec1bc058e8c6e02ab8
Signed-off-by: Anders Kaseorg <andersk@mit.edu>
Reviewed-on: http://gerrit.openafs.org/4057
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Derrick Brashear <shadow@dementia.org>
Tested-by: Derrick Brashear <shadow@dementia.org>
(cherry picked from commit 7350bf894444c05011a3807dd2b69b2d6c2d25c0)