ARM64: VIXL: Fix breaking changes to ternary operator with Register inputs.

Test: mma art
Change-Id: I33d1e05e47f337f1a9271b35dba9227057cda096
diff --git a/compiler/optimizing/common_arm64.h b/compiler/optimizing/common_arm64.h
index 776a483..93ea090 100644
--- a/compiler/optimizing/common_arm64.h
+++ b/compiler/optimizing/common_arm64.h
@@ -130,8 +130,8 @@
   Primitive::Type input_type = input->GetType();
   if (input->IsConstant() && input->AsConstant()->IsZeroBitPattern()) {
     return (Primitive::ComponentSize(input_type) >= vixl::aarch64::kXRegSizeInBytes)
-        ? vixl::aarch64::xzr
-        : vixl::aarch64::wzr;
+        ? vixl::aarch64::Register(vixl::aarch64::xzr)
+        : vixl::aarch64::Register(vixl::aarch64::wzr);
   }
   return InputCPURegisterAt(instr, index);
 }