Fix a few comments in vectorization code that were incorrect or incomplete.

Test: test-art-target
Change-Id: I7c6a5a2d29edd0b2782abc303d8d8cb09c1c2f91
diff --git a/compiler/optimizing/code_generator_x86_64.cc b/compiler/optimizing/code_generator_x86_64.cc
index 49f099f..ff6e099 100644
--- a/compiler/optimizing/code_generator_x86_64.cc
+++ b/compiler/optimizing/code_generator_x86_64.cc
@@ -143,10 +143,10 @@
     LocationSummary* locations = instruction_->GetLocations();
     CodeGeneratorX86_64* x86_64_codegen = down_cast<CodeGeneratorX86_64*>(codegen);
     __ Bind(GetEntryLabel());
-    SaveLiveRegisters(codegen, locations);  // only saves full width XMM for SIMD
+    SaveLiveRegisters(codegen, locations);  // Only saves full width XMM for SIMD.
     x86_64_codegen->InvokeRuntime(kQuickTestSuspend, instruction_, instruction_->GetDexPc(), this);
     CheckEntrypointTypes<kQuickTestSuspend, void, void>();
-    RestoreLiveRegisters(codegen, locations);  // only saves full width XMM for SIMD
+    RestoreLiveRegisters(codegen, locations);  // Only restores full width XMM for SIMD.
     if (successor_ == nullptr) {
       __ jmp(GetReturnLabel());
     } else {