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_sta_iface.h b/wifi/1.0/default/wifi_sta_iface.h
index 5f0ffe9..08faa2f 100644
--- a/wifi/1.0/default/wifi_sta_iface.h
+++ b/wifi/1.0/default/wifi_sta_iface.h
@@ -57,9 +57,8 @@
       installApfPacketFilter_cb hidl_status_cb) override;
   Return<void> getBackgroundScanCapabilities(
       getBackgroundScanCapabilities_cb hidl_status_cb) override;
-  Return<void> getValidFrequenciesForBackgroundScan(
-      StaBackgroundScanBand band,
-      getValidFrequenciesForBackgroundScan_cb hidl_status_cb) override;
+  Return<void> getValidFrequenciesForBand(
+      WifiBand band, getValidFrequenciesForBand_cb hidl_status_cb) override;
   Return<void> startBackgroundScan(
       uint32_t cmd_id,
       const StaBackgroundScanParameters& params,
@@ -119,7 +118,7 @@
   std::pair<WifiStatus, StaBackgroundScanCapabilities>
   getBackgroundScanCapabilitiesInternal();
   std::pair<WifiStatus, std::vector<WifiChannelInMhz>>
-  getValidFrequenciesForBackgroundScanInternal(StaBackgroundScanBand band);
+  getValidFrequenciesForBandInternal(WifiBand band);
   WifiStatus startBackgroundScanInternal(
       uint32_t cmd_id, const StaBackgroundScanParameters& params);
   WifiStatus stopBackgroundScanInternal(uint32_t cmd_id);