cli: pollperiod fix (#387)

src/cli/README.md

@@ -567,20 +567,20 @@ Send an ICMPv6 Echo Request.
 
 ### pollperiod
 
-Get the data poll period of sleepy end device
+Get the customized data poll period of sleepy end device (seconds). Only for certification test
 
 ```bash
 > pollperiod
-240
+0
 Done
 ```
 
 ### pollperiod \<pollperiod>\
 
-Set the data poll period for sleepy end device
+Set the customized data poll period for sleepy end device (seconds). Only for certification test
 
 ```bash
-> pollperiod 240
+> pollperiod 10
 Done
 ```
 

src/cli/cli.cpp

@@ -1040,12 +1040,12 @@ void Interpreter::ProcessPollPeriod(int argc, char *argv[])
 
     if (argc == 0)
     {
-        sServer->OutputFormat("%d\r\n", otGetPollPeriod());
+        sServer->OutputFormat("%d\r\n", (otGetPollPeriod() / 1000));  // ms->s
     }
     else
     {
         SuccessOrExit(error = ParseLong(argv[0], value));
-        otSetPollPeriod(static_cast<uint32_t>(value));
+        otSetPollPeriod(static_cast<uint32_t>(value * 1000));  // s->ms
     }
 
 exit: