[binder] Replace NULL/0 with nullptr

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

clang-tidy -checks=modernize-use-nullptr -p compile_commands.json -fix
...

Test: m
Bug: 68236239
Change-Id: I3181bc5683796423a98b0f9b94daf30880c07bdc
Merged-In: I3181bc5683796423a98b0f9b94daf30880c07bdc
(cherry picked from commit 91635563b8a1bf7a31e4ceb439728dacb79abd76)
diff --git a/libs/binder/tests/schd-dbg.cpp b/libs/binder/tests/schd-dbg.cpp
index 13f03b1..6cf7f36 100644
--- a/libs/binder/tests/schd-dbg.cpp
+++ b/libs/binder/tests/schd-dbg.cpp
@@ -295,7 +295,7 @@
 
   no_inherent += reply.readInt32();
   no_sync += reply.readInt32();
-  return 0;
+  return nullptr;
 }
 
 // create a fifo thread to transact and wait it to finished