sysfs: Fix performance-move-const-arg

```
/home/andrew/src/openbmc/phosphor-led-sysfs/build/../sysfs.cpp:44:53: error: std::move of the const variable 'path' has no effect; remove std::move() or make the variable non-const [performance-move-const-arg,-warnings-as-errors]
    std::string content = getSysfsAttr<std::string>(std::move(path));
                                                    ^~~~~~~~~~    ~
```

Change-Id: I1fd99b58adac8cebecda64166a6929ad6885c366
Signed-off-by: Andrew Jeffery <andrew@aj.id.au>
diff --git a/sysfs.cpp b/sysfs.cpp
index 6039298..09bbc5d 100644
--- a/sysfs.cpp
+++ b/sysfs.cpp
@@ -41,7 +41,7 @@
 template <>
 unsigned long getSysfsAttr(const fs::path& path)
 {
-    std::string content = getSysfsAttr<std::string>(std::move(path));
+    std::string content = getSysfsAttr<std::string>(path);
     return std::strtoul(content.c_str(), nullptr, 0);
 }