Linux: drop GLOCK before calling dput

Linux: drop GLOCK before calling dput

Holding the GLOCK when calling dput can result in a deadlock when
the kernel calls back into afs_dentry_iput.  It should be safe
to drop the lock here.

Reviewed-on: http://gerrit.openafs.org/8046
Reviewed-by: Simon Wilkinson <simonxwilkinson@gmail.com>
Reviewed-by: Derrick Brashear <shadow@your-file-system.com>
Tested-by: Derrick Brashear <shadow@your-file-system.com>
(cherry picked from commit 0dac4de8eee84a43ef06c56dfc867c2a1b9a9f0c)

Change-Id: Ide1dfc73ebc5fa207c19be1c16db9910cf66bea3
Reviewed-on: http://gerrit.openafs.org/8561
Reviewed-by: Ken Dreyer <ktdreyer@ktdreyer.com>
Tested-by: BuildBot <buildbot@rampaginggeek.com>
Reviewed-by: Stephan Wiesand <stephan.wiesand@desy.de>
Tested-by: Stephan Wiesand <stephan.wiesand@desy.de>
Reviewed-by: Paul Smeddle <paul.smeddle@gmail.com>