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/oem/ibm/requester/dbus_to_file_handler.cpp b/oem/ibm/requester/dbus_to_file_handler.cpp
index 47ddf2c..8ed966c 100644
--- a/oem/ibm/requester/dbus_to_file_handler.cpp
+++ b/oem/ibm/requester/dbus_to_file_handler.cpp
@@ -32,7 +32,7 @@
 
 void DbusToFileHandler::sendNewFileAvailableCmd(uint64_t fileSize)
 {
-    if (instanceIdDb == NULL)
+    if (instanceIdDb == nullptr)
     {
         error(
             "Failed to send resource dump parameters as instance ID DB is not set");
@@ -245,7 +245,7 @@
 void DbusToFileHandler::newFileAvailableSendToHost(
     const uint32_t fileSize, const uint32_t fileHandle, const uint16_t type)
 {
-    if (instanceIdDb == NULL)
+    if (instanceIdDb == nullptr)
     {
         error("Failed to send csr to remote terminus.");
         pldm::utils::reportError(