NFC: RFKILL support

All NFC devices will now get proper RFKILL support as long as they provide
some dev_up and dev_down hooks. Rfkilling an NFC device will bring it down
while it is left to userspace to bring it back up when being rfkill unblocked.
This is very similar to what Bluetooth does.

Acked-by: Marcel Holtmann <marcel@holtmann.org>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>