LINUX: create afs_linux_dget() compat wrapper
For dentry operations that cover multiple dentry aliases of
a single inode, create a compatibility wrapper to hide differences
between the older dget_locked() and the current dget().
No functional change should be incurred by this commit.
Change-Id: I2bb0d453417f37707018f6ba5859903c3d34c8ff
Reviewed-on: https://gerrit.openafs.org/12789
Reviewed-by: Andrew Deason <adeason@dson.org>
Reviewed-by: Benjamin Kaduk <kaduk@mit.edu>
Tested-by: BuildBot <buildbot@rampaginggeek.com>