NFC: Add a nfc hardware simulation driver

This driver declares two virtual NFC devices supporting NFC-DEP protocol.
An LLCP connection can be established between them and all packets sent
from one device is sent back to the other, acting as loopback devices.

Once established, the LLCP link can be disconnected by disabling the target
device (with rfkill, nfctool, or neard disable-adapter test script).

Signed-off-by: Thierry Escande <thierry.escande@linux.intel.com>
Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>