clang-tidy: Enable readability-convert-member-functions-to-static

This check finds non-static member functions that can be made
static because the functions don’t use this.
This check also triggers readability-static-accessed-through
-instance check as we are trying to access a static member
function through an instance.

Signed-off-by: George Liu <liuxiwei@ieisystem.com>
Change-Id: I6efe76666f75fb4f65621796466d9347cea25d01
diff --git a/fault-monitor/fru-fault-monitor.hpp b/fault-monitor/fru-fault-monitor.hpp
index fc6cafa..adb6e9b 100644
--- a/fault-monitor/fru-fault-monitor.hpp
+++ b/fault-monitor/fru-fault-monitor.hpp
@@ -67,7 +67,7 @@
     /** @brief function to create fault remove match for a fru
      *  @param[in] path  - Inventory path of the faulty unit.
      */
-    std::string match(const std::string& path)
+    static std::string match(const std::string& path)
     {
         namespace MatchRules = sdbusplus::bus::match::rules;