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/Android.mk b/wifi/1.0/default/Android.mk
index 6180efd..14923f5 100644
--- a/wifi/1.0/default/Android.mk
+++ b/wifi/1.0/default/Android.mk
@@ -21,7 +21,7 @@
     failure_reason_util.cpp \
     wifi_chip.cpp \
     wifi.cpp \
-    wifi_hal_state.cpp
+    wifi_legacy_hal.cpp
 LOCAL_SHARED_LIBRARIES := \
     android.hardware.wifi@1.0 \
     libbase \