AP_InertialSensor: reduce checked register count

thanks to Francisco for spotting this

libraries/AP_InertialSensor/AP_InertialSensor_LSM9DS0.cpp

@@ -473,8 +473,8 @@ bool AP_InertialSensor_LSM9DS0::_hardware_init()
     }
 
     // setup for register checking
-    _dev_gyro->setup_checked_registers(6);
-    _dev_accel->setup_checked_registers(5);
+    _dev_gyro->setup_checked_registers(5);
+    _dev_accel->setup_checked_registers(4);
         
     for (tries = 0; tries < 5; tries++) {
         _dev_gyro->set_speed(AP_HAL::Device::SPEED_LOW);