clean trailing blank characters

SConscript

@@ -1,16 +1,16 @@
 from building import *
 
 cwd = GetCurrentDir()
-    
+
 if GetDepend(['AT_DEVICE_M26']):
     src = Glob('at_socket_m26.c')
-    
+
 if GetDepend(['AT_DEVICE_ESP8266']):
     src = Glob('at_socket_esp8266.c')
-    
+
 if GetDepend(['AT_DEVICE_NOT_SELECTED']):
    src = Glob('*.c')
-    
+
 group = DefineGroup('at_device', src, depend = ['PKG_USING_AT_DEVICE','AT_USING_SOCKET'], CPPPATH = [cwd])
 
 Return('group')

at_client_sample.c

@@ -49,7 +49,7 @@ int at_client_test(int argc, char **argv)
 
     /* close echo */
     at_exec_cmd(resp, "ATE0");
-    
+
     result = at_exec_cmd(resp, "AT+CIFSR");
     if (result != RT_EOK)
     {

at_socket_esp8266.c

@@ -21,7 +21,7 @@
  * Date           Author       Notes
  * 2018-06-20     chenyong     first version
  */
- 
+
 #include <at.h>
 #include <stdio.h>
 #include <string.h>

at_socket_m26.c

@@ -21,7 +21,7 @@
  * Date           Author       Notes
  * 2018-06-12     chenyong     first version
  */
- 
+
 #include <stdio.h>
 #include <string.h>