wifi: Support setBssid for tethered mode hotspot

PS: Remove BSSID convert to WifiConfiguration since BSSID field doesn't
use in WifiConfiguration usage on SoftAp.

Bug: 152180102
Test: atest frameworks/base/wifi/test/
Change-Id: Id781ff6af222fe1d557560feaa44b5d2761c3a81

wifi/java/android/net/wifi/SoftApConfiguration.java

@@ -516,9 +516,6 @@ public final class SoftApConfiguration implements Parcelable {
     public WifiConfiguration toWifiConfiguration() {
         WifiConfiguration wifiConfig = new WifiConfiguration();
         wifiConfig.SSID = mSsid;
-        if (mBssid != null) {
-            wifiConfig.BSSID = mBssid.toString();
-        }
         wifiConfig.preSharedKey = mPassphrase;
         wifiConfig.hiddenSSID = mHiddenSsid;
         wifiConfig.apChannel = mChannel;
@@ -662,8 +659,6 @@ public final class SoftApConfiguration implements Parcelable {
         /**
          * Specifies a BSSID for the AP.
          * <p>
-         * Only supported when configuring a local-only hotspot.
-         * <p>
          * <li>If not set, defaults to null.</li>
          * @param bssid BSSID, or null to have the BSSID chosen by the framework. The caller is
          *              responsible for avoiding collisions.