Revert "Use the "GC is marking" information in compiler read barriers (ARM, ARM64)."

This reverts commit 1372c9f40df1e47bf775f1466bbb96f472b6b9ed.

This change (along with https://android-review.googlesource.com/#/c/342429/)
creates null pointer dereferences.

Bug: 35780827
Bug: 29516974
Change-Id: I2a9c4d0ad8d2ab870c2e0ddbff32152933c77abe
diff --git a/compiler/optimizing/code_generator_arm.h b/compiler/optimizing/code_generator_arm.h
index 1f68777..df2dbc7 100644
--- a/compiler/optimizing/code_generator_arm.h
+++ b/compiler/optimizing/code_generator_arm.h
@@ -520,6 +520,9 @@
                                              Location index,
                                              Location temp,
                                              bool needs_null_check);
+  // Factored implementation used by GenerateFieldLoadWithBakerReadBarrier
+  // and GenerateArrayLoadWithBakerReadBarrier.
+
   // Factored implementation, used by GenerateFieldLoadWithBakerReadBarrier,
   // GenerateArrayLoadWithBakerReadBarrier and some intrinsics.
   //
@@ -542,15 +545,6 @@
                                                  bool always_update_field = false,
                                                  Register* temp2 = nullptr);
 
-  // Generate a heap reference load (with no read barrier).
-  void GenerateRawReferenceLoad(HInstruction* instruction,
-                                Location ref,
-                                Register obj,
-                                uint32_t offset,
-                                Location index,
-                                ScaleFactor scale_factor,
-                                bool needs_null_check);
-
   // Generate a read barrier for a heap reference within `instruction`
   // using a slow path.
   //