Use ParcelFileDescriptor instead of FileDescriptor in INetd.aidl

Stable aidl won't support FileDescriptor but ParcelFileDescriptor.
In order to migrate to stable aidl, replace all FileDescriptor in
INdetd.aidl.

Test: runtest frameworks-net passes
Change-Id: Icdf37aed0e0cce0352070a437066e77c0f2fd85a
diff --git a/tests/net/java/com/android/server/IpSecServiceParameterizedTest.java b/tests/net/java/com/android/server/IpSecServiceParameterizedTest.java
index 4dc0341..d8f9618 100644
--- a/tests/net/java/com/android/server/IpSecServiceParameterizedTest.java
+++ b/tests/net/java/com/android/server/IpSecServiceParameterizedTest.java
@@ -542,7 +542,7 @@
 
         verify(mMockNetd)
                 .ipSecApplyTransportModeTransform(
-                        eq(pfd.getFileDescriptor()),
+                        eq(pfd),
                         eq(mUid),
                         eq(IpSecManager.DIRECTION_OUT),
                         anyString(),
@@ -555,7 +555,7 @@
         ParcelFileDescriptor pfd = ParcelFileDescriptor.fromSocket(new Socket());
         mIpSecService.removeTransportModeTransforms(pfd);
 
-        verify(mMockNetd).ipSecRemoveTransportModeTransform(pfd.getFileDescriptor());
+        verify(mMockNetd).ipSecRemoveTransportModeTransform(pfd);
     }
 
     private IpSecTunnelInterfaceResponse createAndValidateTunnel(