Finish moving TargetRegisterInfo::isVirtualRegister() and friends to llvm::Register as started by r367614. NFC

llvm-svn: 367633
diff --git a/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp b/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
index 2cfbcc5..048e04e 100644
--- a/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
+++ b/llvm/lib/Target/AArch64/AArch64ConditionalCompares.cpp
@@ -259,7 +259,7 @@
   // Writes to the zero register are dead.
   if (DstReg == AArch64::WZR || DstReg == AArch64::XZR)
     return true;
-  if (!TargetRegisterInfo::isVirtualRegister(DstReg))
+  if (!Register::isVirtualRegister(DstReg))
     return false;
   // A virtual register def without any uses will be marked dead later, and
   // eventually replaced by the zero register.