update en/device-dev/driver/driver-platform-dac-des.md.

Signed-off-by: NAnnie_wang <annie.wangli@huawei.com>

en/device-dev/driver/driver-platform-dac-des.md

@@ -46,7 +46,7 @@ The DAC module is divided into the following layers:
 
 **Figure 1** Unified service mode
 
-![Unified service mode](figures/unified_service_mode.png "DAC unified service mode")
+![](figures/unified-service-mode.png "DAC-unified-service-mode")
 
 ### Constraints
 
@@ -76,7 +76,7 @@ The figure below illustrates the process of using a DAC device.
 
 **Figure 2** Process of using a DAC device
  
-![Process of using a DAC](figures/process_of_using_DAC.png"Process of using a DAC")
+![](figures/process-of-using-DAC.png "Process of using a DAC")
 
 #### Opening a DAC Device