We need to init the gyro subdevice, or there is no device node. Oops.

apps/drivers/mpu6000/mpu6000.cpp

@@ -430,6 +430,8 @@ MPU6000::init()
 	// write_reg(MPUREG_PWR_MGMT_1,MPU_CLK_SEL_PLLGYROZ);
 	usleep(1000);
 
+	/* do CDev init for the gyro device node */
+	ret = _gyro->init();
 
 	return ret;
 }