Don't prevent notification updates in DOS protection.

The NotificationManagerService limits the number of
notifications per package+user to 50. Once that limit is
reached, it will refuse new notifications. However, it was
also erroneously refusing updates to existing notifications.

Bug: 5821364
Change-Id: I3aa4be9ad4b288e4a22bf7a64f67521695dfb579
1 file changed