wifi_hal : Need not check for hal_info validity in Wi-Fi HAL API's.

Wi-Fi HAL API's , are invoked from the legacy hal context
and it is this legacy hal that validates the context of hal_info.
It is the legacy_hal that triggers the start / stop / event loop for
Wi-Fi HAL. Thus, the validity of hal_info should be left to lagacy
hal rather than validating in all the API's of Wi-Fi HAL.

Change-Id: I9457c5ab7725d489078af0a9b8eb26b9cb5eb6ec
CRs-Fixed: 2588277