clang-tidy: enable clang-tidy

Enable the first check: readability-identifier-naming

Also fixed all check failures. The renaming is done by clang-tidy
automatically.

Tested:
1. compiles, no clang-tidy failures
2. tested on QEMU, Redfish is working correctly
3. tested on s7106, Redfish is working correctly; certificates can be
   retrieved.

Signed-off-by: Nan Zhou <nanzhoumails@gmail.com>
Change-Id: I3c5c9ca734146a94f4e0433ed8c1ae84173288c5
diff --git a/csr.cpp b/csr.cpp
index 5caed9d..5f400e5 100644
--- a/csr.cpp
+++ b/csr.cpp
@@ -43,7 +43,7 @@
 
 std::string CSR::csr()
 {
-    if (csrStatus == Status::FAILURE)
+    if (csrStatus == Status::failure)
     {
         log<level::ERR>("Failure in Generating CSR");
         elog<InternalFailure>();