wifi: create a new IMS network callback on starting deferring handler

Network lost events might not be received before the deferring timeout
and network count is kept in the object. This will accumulate the network count
incorrectly and always trigger wifi off deferring.

Creating a new callbck object on starting the deferring handler to
ensure that all internal data are cleared.

Bug: 190512258
Test: atest FrameworksWifiTests
Change-Id: I5fa9f81132b25d82347679c4ca1152f8a9c19536
1 file changed