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/pldmtool/oem/ibm/pldm_oem_ibm.cpp b/pldmtool/oem/ibm/pldm_oem_ibm.cpp
index 317dbfa..5f96654 100644
--- a/pldmtool/oem/ibm/pldm_oem_ibm.cpp
+++ b/pldmtool/oem/ibm/pldm_oem_ibm.cpp
@@ -159,7 +159,7 @@
 
     void printFileAttrTable(uint8_t* data, size_t length)
     {
-        if (data == NULL || length == 0)
+        if (data == nullptr || length == 0)
         {
             return;
         }