wifi: Restructure wifi legacy HAL implementation

Restructured the existing code to create a new class called
|WifiLegacyHal|. This class will be used as a wrapper to invoke
all the legacy HAL functions and handle the "C" style callbacks.

Bug: 31936700
Test: mmma -j32 hardware/interfaces/wifi/1.0/default
Change-Id: I63e8543f49886f8446101320a97d1e96e30d1035
diff --git a/wifi/1.0/default/service.cpp b/wifi/1.0/default/service.cpp
index 07e6c81..10ce1db 100644
--- a/wifi/1.0/default/service.cpp
+++ b/wifi/1.0/default/service.cpp
@@ -55,13 +55,14 @@
 
   // Setup hwbinder service
   android::sp<android::hardware::wifi::V1_0::IWifi> service =
-      new android::hardware::wifi::V1_0::implementation::Wifi(looper);
+      new android::hardware::wifi::V1_0::implementation::Wifi();
   CHECK_EQ(service->registerAsService("wifi"), android::NO_ERROR)
       << "Failed to register wifi HAL";
 
   // Loop
-  while (looper->pollAll(-1) != Looper::POLL_ERROR)
-    ;
+  while (looper->pollAll(-1) != Looper::POLL_ERROR) {
+    // Keep polling until failure.
+  }
 
   LOG(INFO) << "wifi_hal_legacy is terminating...";
   return 0;