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/x509_utils.cpp b/x509_utils.cpp
index ba1a2ef..4c8cc3a 100644
--- a/x509_utils.cpp
+++ b/x509_utils.cpp
@@ -217,10 +217,10 @@
 {
     unsigned long subjectNameHash = X509_subject_name_hash(&cert);
     unsigned long issuerSerialHash = X509_issuer_and_serial_hash(&cert);
-    static constexpr auto CERT_ID_LENGTH = 17;
-    char idBuff[CERT_ID_LENGTH];
+    static constexpr auto certIdLength = 17;
+    char idBuff[certIdLength];
 
-    snprintf(idBuff, CERT_ID_LENGTH, "%08lx%08lx", subjectNameHash,
+    snprintf(idBuff, certIdLength, "%08lx%08lx", subjectNameHash,
              issuerSerialHash);
 
     return {idBuff};