[mlir] Use a new constructor of ArrayRef (NFC)

ArrayRef now has a new constructor that takes a parameter whose type
has data() and size().  This patch migrates:

  ArrayRef<T>(X.data(), X.size()

to:

  ArrayRef<T>(X)

Author: kazutakahirata

mlir/lib/AsmParser/AttributeParser.cpp

@@ -717,7 +717,7 @@ DenseElementsAttr TensorLiteralParser::getHexAttr(SMLoc loc, ShapedType type) {
   if (parseElementAttrHexValues(p, *hexStorage, data))
     return nullptr;
 
-  ArrayRef<char> rawData(data.data(), data.size());
+  ArrayRef<char> rawData(data);
   bool detectedSplat = false;
   if (!DenseElementsAttr::isValidRawBuffer(type, rawData, detectedSplat)) {
     p.emitError(loc) << "elements hex data size is invalid for provided type: "

mlir/lib/Target/LLVMIR/ModuleTranslation.cpp

@@ -727,10 +727,8 @@ llvm::Constant *mlir::LLVM::detail::getLLVMConstant(
   }
 
   if (auto stringAttr = dyn_cast<StringAttr>(attr)) {
-    return llvm::ConstantDataArray::get(
-        moduleTranslation.getLLVMContext(),
-        ArrayRef<char>{stringAttr.getValue().data(),
-                       stringAttr.getValue().size()});
+    return llvm::ConstantDataArray::get(moduleTranslation.getLLVMContext(),
+                                        ArrayRef<char>{stringAttr.getValue()});
   }
 
   // Handle arrays of structs that cannot be represented as DenseElementsAttr