[input] Modernize codebase by replacing NULL with nullptr

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

Test: m
Bug: 68236239
Change-Id: I8882234efd2a0b3ef27472d3f5d4e9c69c6e7b37
diff --git a/libs/input/VirtualKeyMap.cpp b/libs/input/VirtualKeyMap.cpp
index 28ea717..9932973 100644
--- a/libs/input/VirtualKeyMap.cpp
+++ b/libs/input/VirtualKeyMap.cpp
@@ -47,7 +47,7 @@
 }
 
 status_t VirtualKeyMap::load(const String8& filename, VirtualKeyMap** outMap) {
-    *outMap = NULL;
+    *outMap = nullptr;
 
     Tokenizer* tokenizer;
     status_t status = Tokenizer::open(filename, &tokenizer);