Disable per channel quantization for FC layers (#2465)

BUG=b/324385802

tensorflow/lite/micro/testing/generate_test_models.py

diff --git a/tensorflow/lite/micro/testing/generate_test_models.py b/tensorflow/lite/micro/testing/generate_test_models.py
index 25902d0..2593653 100644
--- a/tensorflow/lite/micro/testing/generate_test_models.py
+++ b/tensorflow/lite/micro/testing/generate_test_models.py
@@ -71,6 +71,10 @@
   converter.inference_input_type = tf.int8
   converter.inference_output_type = tf.int8
   converter.representative_dataset = representative_dataset_gen
+  # TODO(b/324385802): Disable per channel quantization in FC layers (currently
+  # default behaviour) since it's not yet supported in TFLM.
+  converter._experimental_disable_per_channel_quantization_for_dense_layers = (  # pylint: disable=protected-access
+      True)
 
   tflite_model = converter.convert()
   if write_to_file:

tensorflow/lite/micro/tools/requantize_flatbuffer_test.py

diff --git a/tensorflow/lite/micro/tools/requantize_flatbuffer_test.py b/tensorflow/lite/micro/tools/requantize_flatbuffer_test.py
index 4d80991..04bbb32 100644
--- a/tensorflow/lite/micro/tools/requantize_flatbuffer_test.py
+++ b/tensorflow/lite/micro/tools/requantize_flatbuffer_test.py
@@ -60,6 +60,10 @@
         EXPERIMENTAL_TFLITE_BUILTINS_ACTIVATIONS_INT16_WEIGHTS_INT8
     ]
   converter.representative_dataset = representative_dataset_gen
+  # TODO(b/324385802): Disable per channel quantization in FC layers (currently
+  # default behaviour) since it's not yet supported in TFLM.
+  converter._experimental_disable_per_channel_quantization_for_dense_layers = (  # pylint: disable=protected-access
+      True)
   return converter.convert()