[mlir][acc] Use consistent name for device_num operand

`acc.set`, `acc.init`, and `acc.shutdown` take a `device_num` operand.
However, this was named inconsistently. Give it the same consistent
name for all aforementioned operations.

Author: Razvan Lupusoru

mlir/include/mlir/Dialect/OpenACC/OpenACCOps.td

@@ -2611,11 +2611,11 @@ def OpenACC_InitOp : OpenACC_Op<"init", [AttrSizedOperandSegments]> {
   }];
 
   let arguments = (ins OptionalAttr<TypedArrayAttrBase<OpenACC_DeviceTypeAttr, "Device type attributes">>:$device_types,
-                       Optional<IntOrIndex>:$deviceNumOperand,
+                       Optional<IntOrIndex>:$deviceNum,
                        Optional<I1>:$ifCond);
 
   let assemblyFormat = [{
-    oilist(`device_num` `(` $deviceNumOperand `:` type($deviceNumOperand) `)`
+    oilist(`device_num` `(` $deviceNum `:` type($deviceNum) `)`
       | `if` `(` $ifCond `)`
     ) attr-dict-with-keyword
   }];
@@ -2642,11 +2642,11 @@ def OpenACC_ShutdownOp : OpenACC_Op<"shutdown", [AttrSizedOperandSegments]> {
   }];
 
   let arguments = (ins OptionalAttr<TypedArrayAttrBase<OpenACC_DeviceTypeAttr, "Device type attributes">>:$device_types,
-                       Optional<IntOrIndex>:$deviceNumOperand,
+                       Optional<IntOrIndex>:$deviceNum,
                        Optional<I1>:$ifCond);
 
   let assemblyFormat = [{
-    oilist(`device_num` `(` $deviceNumOperand `:` type($deviceNumOperand) `)`
+    oilist(`device_num` `(` $deviceNum `:` type($deviceNum) `)`
     |`if` `(` $ifCond `)`
     ) attr-dict-with-keyword
   }];