wifi: Changes to WifiLegacy Hal

Changes in the CL:
a. Removed the usage of wifi_status_util in WifiLegacyHal. The
|legacyErrorToString| log will be done in the HIDL object. This is to
remove any reference of |WifiStatus|
b. Moved the cleanup of function pointers to a separate helper function
|invalidate|.
c. Moved static constants out of WifiLegacyHal class.

Bug: 32505551
Test: Compiles
Change-Id: I9dc3900c40cf30de2c0a4376d4de2b08076e2b5f
diff --git a/wifi/1.0/default/wifi.cpp b/wifi/1.0/default/wifi.cpp
index 73b921a..fd2cb9c 100644
--- a/wifi/1.0/default/wifi.cpp
+++ b/wifi/1.0/default/wifi.cpp
@@ -99,7 +99,8 @@
   LOG(INFO) << "Starting HAL";
   wifi_error legacy_status = legacy_hal_->start();
   if (legacy_status != WIFI_SUCCESS) {
-    LOG(ERROR) << "Failed to start Wifi HAL";
+    LOG(ERROR) << "Failed to start Wifi HAL: "
+               << legacyErrorToString(legacy_status);
     return createWifiStatusFromLegacyError(legacy_status,
                                            "Failed to start HAL");
   }
@@ -139,7 +140,8 @@
   };
   wifi_error legacy_status = legacy_hal_->stop(on_complete_callback_);
   if (legacy_status != WIFI_SUCCESS) {
-    LOG(ERROR) << "Failed to stop Wifi HAL";
+    LOG(ERROR) << "Failed to stop Wifi HAL: "
+               << legacyErrorToString(legacy_status);
     WifiStatus wifi_status =
         createWifiStatusFromLegacyError(legacy_status, "Failed to stop HAL");
     for (const auto& callback : event_callbacks_) {