nfc: pn533: Add autopoll capability

pn532 devices support an autopoll command, that lets the chip
automatically poll for selected nfc technologies instead of manually
looping through every single nfc technology the user is interested in.
This is faster and less cpu and bus intensive than manually polling.
This adds this autopoll capability to the pn533 driver.

Cc: Johan Hovold <johan@kernel.org>
Cc: David Miller <davem@davemloft.net>
Signed-off-by: Lars Poeschel <poeschel@lemonage.de>
Signed-off-by: David S. Miller <davem@davemloft.net>