Do not treat EXTRA_SMALL_ICON <int> as Parcelable

It isn't one, and I should have read the documentation on it properly
before treating it the same as EXTRA_LARGE_ICON (which is indeed a
Parcelable).

This fixes a chronic outpouring of technically-probably-harmless warning
stack traces of the following nature which can be verified by running
the framework tests and grepping logcat for this scary-looking string:

  java.lang.ClassCastException: java.lang.Integer cannot be cast to
  android.os.Parcelable
    at android.os.Bundle.getParcelable(Bundle.java:***)
    at android.app.Notification.fixDuplicateExtra
    at android.app.Notification.fixDuplicateExtras
    at android.app.Notification.readFromParcelImpl

Duplicate Integer objects are harmless compared to the Bitmap so there
is zero sense in recombining the objects after an RPC. We just drop the
line which tries to do that.

Test: make FrameworksCoreTests -j30 && \
Test: adb install -r ${ANDROID_PRODUCT_OUT}/data/app/*/FrameworksCoreTests.apk && \
Test: adb shell am instrument \
Test:   -e class android.app.NotificationTest \
Test:   -w com.android.frameworks.coretests/android.support.test.runner.AndroidJUnitRunner
Change-Id: I2c88ab4e9d5322c05e2e7f68df85ed5b2f296f84
Bug: 79404137