Update pwm.c

rt_malloc -> rt_calloc

bsp/fh8620/drivers/pwm.c

@@ -185,16 +185,14 @@ int fh_pwm_probe(void *priv_data)
 
     PWM_Enable(pwm_obj, RT_FALSE);
 
-    pwm_dev = rt_malloc(sizeof(struct rt_device));
+    pwm_dev = rt_calloc(sizeof(struct rt_device));
 
     if (pwm_dev == RT_NULL)
     {
-        rt_kprintf("ERROR: %s rt_device malloc failed\n", __func__);
-        return -RT_EIO;
+        rt_kprintf("ERROR: %s rt_device calloc failed\n", __func__);
+        return -RT_ENOMEM;
     }
     
-    rt_memset(pwm_dev, 0, sizeof(struct rt_device));
-
     pwm_dev->user_data = &pwm_drv;
     pwm_dev->open =fh_pwm_open;
     pwm_dev->close = fh_pwm_close;