expose systemAPI for SmsCbLocation constructor

Bug: 135956699
Test: cts SmsCbLocationTest
Change-Id: I7b9c6fa453ee907aaa13d65e0b13de0556852313

api/system-current.txt

@@ -8311,6 +8311,7 @@ package android.telephony {
   }
 
   public final class SmsCbLocation implements android.os.Parcelable {
+    ctor public SmsCbLocation(@NonNull String, int, int);
     method public int describeContents();
     method public int getCid();
     method public int getLac();

telephony/java/android/telephony/SmsCbLocation.java

@@ -65,9 +65,8 @@ public final class SmsCbLocation implements Parcelable {
     /**
      * Construct a location object for the PLMN, LAC, and Cell ID. This class is immutable, so
      * the same object can be reused for multiple broadcasts.
-     * @hide
      */
-    public SmsCbLocation(String plmn, int lac, int cid) {
+    public SmsCbLocation(@NonNull String plmn, int lac, int cid) {
         mPlmn = plmn;
         mLac = lac;
         mCid = cid;