nfs: Remove redundant null checks before kfree

Fix the following coccicheck warning:
fs/nfs/dir.c:2494:2-7: WARNING:
NULL check before some freeing functions is not needed.
Signed-off-by: Yushan Zhou <katrinzhou@tencent.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/dir.c

@@ -2489,9 +2489,8 @@ int nfs_unlink(struct inode *dir, struct dentry *dentry)
 		spin_unlock(&dentry->d_lock);
 		goto out;
 	}
-	if (dentry->d_fsdata)
-		/* old devname */
-		kfree(dentry->d_fsdata);
+	/* old devname */
+	kfree(dentry->d_fsdata);
 	dentry->d_fsdata = NFS_FSDATA_BLOCKED;
 
 	spin_unlock(&dentry->d_lock);