NFS: Fix wakeup of __nfs_lookup_revalidate() in unblock_revalidate()

NFS: Fix wakeup of __nfs_lookup_revalidate() in unblock_revalidate()

Use store_release_wake_up() to add the appropriate memory barrier before
calling wake_up_var(&dentry->d_fsdata).

Reported-by: Lukáš Hejtmánek<xhejtman@ics.muni.cz>
Suggested-by: Santosh Pradhan <santosh.pradhan@gmail.com>
Link: https://lore.kernel.org/all/18945D18-3EDB-4771-B019-0335CE671077@ics.muni.cz/
Fixes: 99bc9f2eb3f7 ("NFS: add barriers when testing for NFS_FSDATA_BLOCKED")
Signed-off-by: Trond Myklebust <trond.myklebust@hammerspace.com>