btrfs: Cleanup some redundant codes in btrfs_log_inode()

Signed-off-by: Zhi Yong Wu <wuzhy@linux.vnet.ibm.com>
Signed-off-by: Josef Bacik <jbacik@fusionio.com>
diff --git a/fs/btrfs/tree-log.c b/fs/btrfs/tree-log.c
index ef96381..f728eeb 100644
--- a/fs/btrfs/tree-log.c
+++ b/fs/btrfs/tree-log.c
@@ -3650,8 +3650,6 @@
 	bool fast_search = false;
 	u64 ino = btrfs_ino(inode);
 
-	log = root->log_root;
-
 	path = btrfs_alloc_path();
 	if (!path)
 		return -ENOMEM;