add channels to the notification functional tests

Bug: 65552160
Test: mmma -j20 platform_testing/tests/functional/notificationtests && adb install -r -g /mnt/fastroid/oc-mr1-dev/out/target/product/sailfish/data/app/NotificationFunctionalTests/NotificationFunctionalTests.apk && adb shell am instrument -w -e iterations 1 -e class com.android.notification.functional.NotificationInteractionTests com.android.notification.functional/android.support.test.runner.AndroidJUnitRunner
Change-Id: Ibf8ca0567772574964c45a130f69d0ac3aa6922c