[NVPTX] Remove unused private field in NVVMIntrRange.cpp (NFC)

/llvm-project/llvm/lib/Target/NVPTX/NVVMIntrRange.cpp:33:12:
error: private field 'SmVersion' is not used [-Werror,-Wunused-private-field]
  unsigned SmVersion;
           ^
1 error generated.

Author: DamonFool

llvm/lib/Target/NVPTX/NVVMIntrRange.cpp

@@ -30,8 +30,6 @@ namespace llvm { void initializeNVVMIntrRangePass(PassRegistry &); }
 
 namespace {
 class NVVMIntrRange : public FunctionPass {
-  unsigned SmVersion;
-
 public:
   static char ID;
   NVVMIntrRange() : FunctionPass(ID) {