Fix return value of rt_dac_write function. (#5816)

Co-authored-by: NWayne Lin <wclin@nuvoton.com>

components/drivers/include/drivers/dac.h

@@ -35,7 +35,7 @@ typedef enum
 
 rt_err_t rt_hw_dac_register(rt_dac_device_t dac,const char *name, const struct rt_dac_ops *ops, const void *user_data);
 
-rt_uint32_t rt_dac_write(rt_dac_device_t dev, rt_uint32_t channel, rt_uint32_t value);
+rt_err_t rt_dac_write(rt_dac_device_t dev, rt_uint32_t channel, rt_uint32_t value);
 rt_err_t rt_dac_enable(rt_dac_device_t dev, rt_uint32_t channel);
 rt_err_t rt_dac_disable(rt_dac_device_t dev, rt_uint32_t channel);
 

components/drivers/misc/dac.c

@@ -98,13 +98,11 @@ rt_err_t rt_hw_dac_register(rt_dac_device_t device, const char *name, const stru
     return result;
 }
 
-rt_uint32_t rt_dac_write(rt_dac_device_t dev, rt_uint32_t channel, rt_uint32_t value)
+rt_err_t rt_dac_write(rt_dac_device_t dev, rt_uint32_t channel, rt_uint32_t value)
 {
     RT_ASSERT(dev);
 
-    dev->ops->convert(dev, channel, &value);
-
-    return RT_EOK;
+    return dev->ops->convert(dev, channel, &value);
 }
 
 rt_err_t rt_dac_enable(rt_dac_device_t dev, rt_uint32_t channel)