Fixed PWM assertion error caused by using DM

components/drivers/misc/rt_drv_pwm.c

@@ -116,7 +116,9 @@ rt_err_t rt_device_pwm_register(struct rt_device_pwm *device, const char *name,
 {
     rt_err_t result = RT_EOK;
 
+#ifndef RT_USING_DM
     rt_memset(device, 0, sizeof(struct rt_device_pwm));
+#endif
 
 #ifdef RT_USING_DEVICE_OPS
     device->parent.ops = &pwm_device_ops;