clang-tidy: Replace NULL with nullptr

Replaced all instances of NULL with nullptr to improve type safety
and clarity, as nullptr is the modern C++ standard for null pointers.

Tested: Build verified

Change-Id: If9e6c34c48821a7cf8577a2166727ce7db06fadc
Signed-off-by: Jayanth Othayoth <ojayanth@gmail.com>
diff --git a/platform-mc/terminus_manager.cpp b/platform-mc/terminus_manager.cpp
index 7565ee2..56902ad 100644
--- a/platform-mc/terminus_manager.cpp
+++ b/platform-mc/terminus_manager.cpp
@@ -490,7 +490,7 @@
         co_return rc;
     }
 
-    if (responseMsg == NULL || responseLen != PLDM_SET_TID_RESP_BYTES)
+    if (responseMsg == nullptr || responseLen != PLDM_SET_TID_RESP_BYTES)
     {
         lg2::error(
             "Failed to decode response SetTID for Endpoint ID {EID}, error {RC} ",