Fix swapped toast timeouts.

LONG and SHORT were swapped. Also they weren't related to the
actual timeout values in NotificationManagerService. Set the timeout
to twice the duration. Just proposing to master since all the
toast timeout does in N is strip the FLAG_KEEP_SCREEN_ON_FLAG.

Change-Id: I5533e03b45d8f9518919b19ec53fc839443f8886