wifi: Duplicate getValidChannelsForBand in AP iface

This functionality is needed even for AP iface. So, duplicate this
method.

Changes in the CL:
1. Add getValidChannelsForBand() in IWifiApIface.
2. Rename StaBackgroundScanBan to WifiBand to make it a more generic
name.
3. Change the existing method name in IWifiStaIface to match with the
one in IWifiApIface.

While there,
Fix indentation in hidl_callback_util.h

Bug: 35663149
Test: Compiles
Change-Id: Iaeb6c323e13eedf2f98de92fea77e327c76ffa5b
diff --git a/wifi/1.0/default/wifi_ap_iface.cpp b/wifi/1.0/default/wifi_ap_iface.cpp
index 1a8b31d..e2beec2 100644
--- a/wifi/1.0/default/wifi_ap_iface.cpp
+++ b/wifi/1.0/default/wifi_ap_iface.cpp
@@ -17,6 +17,7 @@
 #include <android-base/logging.h>
 
 #include "hidl_return_util.h"
+#include "hidl_struct_util.h"
 #include "wifi_ap_iface.h"
 #include "wifi_status_util.h"
 
@@ -64,6 +65,15 @@
                          code);
 }
 
+Return<void> WifiApIface::getValidFrequenciesForBand(
+    WifiBand band, getValidFrequenciesForBand_cb hidl_status_cb) {
+  return validateAndCall(this,
+                         WifiStatusCode::ERROR_WIFI_IFACE_INVALID,
+                         &WifiApIface::getValidFrequenciesForBandInternal,
+                         hidl_status_cb,
+                         band);
+}
+
 std::pair<WifiStatus, std::string> WifiApIface::getNameInternal() {
   return {createWifiStatus(WifiStatusCode::SUCCESS), ifname_};
 }
@@ -79,6 +89,16 @@
   return createWifiStatusFromLegacyError(legacy_status);
 }
 
+std::pair<WifiStatus, std::vector<WifiChannelInMhz>>
+WifiApIface::getValidFrequenciesForBandInternal(WifiBand band) {
+  static_assert(sizeof(WifiChannelInMhz) == sizeof(uint32_t), "Size mismatch");
+  legacy_hal::wifi_error legacy_status;
+  std::vector<uint32_t> valid_frequencies;
+  std::tie(legacy_status, valid_frequencies) =
+      legacy_hal_.lock()->getValidFrequenciesForBand(
+          hidl_struct_util::convertHidlWifiBandToLegacy(band));
+  return {createWifiStatusFromLegacyError(legacy_status), valid_frequencies};
+}
 }  // namespace implementation
 }  // namespace V1_0
 }  // namespace wifi