Fixed overflow risk when `poll_timeout` is 1s,
although it is not recommended to use it like this,
when it is used like this, `POLL_TIMEOUT_MAX`
will overflow.
When the poll timeout set like above, the default `6`
req_attemps for first pull request lost,
may cause this procedure bigger than poll_timeout,
Well, stop scanning when lpn terminated friendship,
this will save lots of energy, when lpn mode enable,
the scanning will be start after `FRIEND_REQ_RETRY_TIMEOUT`
Signed-off-by: Lingao Meng <mengabc1086@gmail.com>
3b4d58aa4b