Temporarily remove xfce4-sensors-plugin, then try again. After the successful installation of the drivers, you can reinstall it.
sudo pacman -Rdd xfce4-sensors-plugin
Note that I edited your post to fix the formatting–this time. 
In the future, please use proper formatting. Using quotes for file and terminal output are not acceptable and are hard to read. Please see [HowTo] Post command output and file content as preformatted text