Added DMA and DMA synchronizer.

Pulled the dma setters out of year specific.

Change-Id: I4e797df52aa07edb5515f941113e7b43747622c9
diff --git a/frc971/wpilib/sensor_reader.cc b/frc971/wpilib/sensor_reader.cc
index f2123a1..38989a4 100644
--- a/frc971/wpilib/sensor_reader.cc
+++ b/frc971/wpilib/sensor_reader.cc
@@ -10,6 +10,11 @@
 
 SensorReader::SensorReader() {}
 
+void SensorReader::set_dma(::std::unique_ptr<DMA> dma) {
+  dma_synchronizer_.reset(
+      new ::frc971::wpilib::DMASynchronizer(::std::move(dma)));
+}
+
 void SensorReader::set_pwm_trigger(
     ::std::unique_ptr<frc::DigitalInput> pwm_trigger) {
   medium_encoder_filter_.Add(pwm_trigger.get());