Modernize codebase by replacing NULL with nullptr

Fixes -Wzero-as-null-pointer-constant warning.

Test: m
Bug: 68236239
Change-Id: I5b4123bc6709641315120a191e36cc57541349b2
diff --git a/benchmarks/property_benchmark.cpp b/benchmarks/property_benchmark.cpp
index 17e37b0..9251a05 100644
--- a/benchmarks/property_benchmark.cpp
+++ b/benchmarks/property_benchmark.cpp
@@ -163,7 +163,7 @@
 
   size_t i = 0;
   while (state.KeepRunning()) {
-    pa.system_properties().Read(pinfo[i], 0, propvalue);
+    pa.system_properties().Read(pinfo[i], nullptr, propvalue);
     i = (i + 1) % nprops;
   }