[mlir] Remove unused forward declaration QuantizedIntegerType

The declaration was added without a corresponding class definition by:

  commit 13bb8f491a1cb429226768cfd4ca6bcea3b938dd
  Author: Stella Laurenzo <laurenzo@google.com>
  Date:   Wed Apr 3 11:16:32 2019 -0700

diff --git a/mlir/include/mlir/Dialect/Quant/QuantTypes.h b/mlir/include/mlir/Dialect/Quant/QuantTypes.h
index 260a9ba..2776b3e 100644 (file)
--- a/mlir/include/mlir/Dialect/Quant/QuantTypes.h
+++ b/mlir/include/mlir/Dialect/Quant/QuantTypes.h
@@ -19,9 +19,6 @@
 
 namespace mlir {
 namespace quant {
-
-class QuantizedIntegerType;
-
 namespace detail {
 
 struct QuantizedTypeStorage;