Restrict RF Field events to preferred app.

If any of the packages in nfcee_extras.xml
is preferred (either tap&pay or foreground),
only that app will get RF field events. Otherwise,
all apps in nfcee_extras will get the events.

Long term solution will be to reduce reliance
on RF field events (which doesn't scale), and instead
tie this to AID selection.

Bug: 18358874
Change-Id: I29276b8929f48b8ca33d61c4120a7405c0ab4dcf