btrfs: Remove never reached error handling code in __add_reloc_root

One of the error handling paths in __add_reloc_root contains btrfs_panic()
followed by some other code. As the name implies what it does is print
some error message and call BUG, naturally what follow afterwards is not
invoked. So remove this extra code.
Signed-off-by: NNikolay Borisov <nborisov@suse.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>

fs/btrfs/relocation.c

@@ -1308,8 +1308,6 @@ static int __must_check __add_reloc_root(struct btrfs_root *root)
 		btrfs_panic(fs_info, -EEXIST,
 			    "Duplicate root found for start=%llu while inserting into relocation tree",
 			    node->bytenr);
-		kfree(node);
-		return -EEXIST;
 	}
 
 	list_add_tail(&root->root_list, &rc->reloc_roots);