Handle file errors when device path gets unbound

occ-control was asserting when the hwmon path would get removed due to
device being unbound. This change will gracefully handle the path
getting removed / added back.

Tested on Raininer by unbind/bind of devices:
  echo occ-hwmon.2 > /sys/bus/platform/drivers/occ-hwmon/unbind
  echo occ-hwmon.2 > /sys/bus/platform/drivers/occ-hwmon/bind

Change-Id: I46fd2c2c54868ffb8183d3dc49cd0c2751165d3b
Signed-off-by: Chris Cain <cjcain@us.ibm.com>
diff --git a/occ_device.hpp b/occ_device.hpp
index 97bdceb..3c11d13 100644
--- a/occ_device.hpp
+++ b/occ_device.hpp
@@ -283,17 +283,8 @@
      *
      *  @return path to the file or empty path if not found
      */
-    fs::path getFilenameByRegex(fs::path basePath, const std::regex& expr) const
-    {
-        for (auto& file : fs::directory_iterator(basePath))
-        {
-            if (std::regex_search(file.path().string(), expr))
-            {
-                return file;
-            }
-        }
-        return fs::path{};
-    }
+    fs::path getFilenameByRegex(fs::path basePath,
+                                const std::regex& expr) const;
 };
 
 } // namespace occ