Remove unused import in IpSecAlgorithm

HexDump is an internal class which cannot be visible to mainline
module. Remove it since this is unused.

Bug: 204153604
Test: FrameworksNetTests
Change-Id: Ie65e7eff8464487719c3124005a097a500ba21c6
diff --git a/framework-t/src/android/net/IpSecAlgorithm.java b/framework-t/src/android/net/IpSecAlgorithm.java
index 5e647fe..a84e7a9 100644
--- a/framework-t/src/android/net/IpSecAlgorithm.java
+++ b/framework-t/src/android/net/IpSecAlgorithm.java
@@ -23,7 +23,6 @@
 import android.os.Parcelable;
 
 import com.android.internal.annotations.VisibleForTesting;
-import com.android.internal.util.HexDump;
 
 import java.lang.annotation.Retention;
 import java.lang.annotation.RetentionPolicy;