Zero initialize strided slice op params. (#1980)

This is so that a new field may safely be added.

BUG=http://b/260574895

tensorflow/lite/micro/kernels/strided_slice.cc

@@ -69,7 +69,7 @@ const int kMaxDim = 4;
 
 tflite::StridedSliceParams BuildStridedSliceParams(
     StridedSliceContext* op_context) {
-  tflite::StridedSliceParams op_params;
+  tflite::StridedSliceParams op_params{};
   op_params.start_indices_count = op_context->dims;
   op_params.stop_indices_count = op_context->dims;
   op_params.strides_count = op_context->dims;