Work around bug in the SPI driver

This makes the IMU start and restart reliably.

Also remove the gyro to avoid having to coordinate with that thread.

Change-Id: I0645a4b47f76c479bf479629c8c8ad5c6dab98ef
diff --git a/frc971/wpilib/ADIS16448.h b/frc971/wpilib/ADIS16448.h
index 4f2aaa0..52090a1 100644
--- a/frc971/wpilib/ADIS16448.h
+++ b/frc971/wpilib/ADIS16448.h
@@ -12,6 +12,7 @@
 #undef ERROR
 
 #include "aos/common/logging/logging.h"
+#include "frc971/wpilib/spi_rx_clearer.h"
 
 namespace frc971 {
 namespace wpilib {
@@ -95,6 +96,8 @@
   double gyro_x_zeroed_offset_ = 0.0;
   double gyro_y_zeroed_offset_ = 0.0;
   double gyro_z_zeroed_offset_ = 0.0;
+
+  SpiRxClearer rx_clearer_;
 };
 
 }  // namespace wpilib