wifi: Add supported channel list in SoftApCapability

Support API: get current supported channel list

Bug: 151189102
Test: atest frameworks/base/wifi/tests
Change-Id: I2decc0764243fb61e3b42b83eb04f83fab2270db
diff --git a/wifi/api/system-current.txt b/wifi/api/system-current.txt
index 985ff1d..53c69c4 100644
--- a/wifi/api/system-current.txt
+++ b/wifi/api/system-current.txt
@@ -241,6 +241,7 @@
     method public boolean areFeaturesSupported(long);
     method public int describeContents();
     method public int getMaxSupportedClients();
+    method @NonNull public int[] getSupportedChannelList(int);
     method public void writeToParcel(@NonNull android.os.Parcel, int);
     field @NonNull public static final android.os.Parcelable.Creator<android.net.wifi.SoftApCapability> CREATOR;
     field public static final long SOFTAP_FEATURE_ACS_OFFLOAD = 1L; // 0x1L