NFC: netlink: Implement vendor command support

Vendor commands are passed from userspace through the
NFC_CMD_VENDOR netlink command, allowing driver and hardware
specific operations implementations like for example RF tuning
or production line calibration.

Drivers will associate a set of vendor commands to a vendor
id, which could typically be an OUI. The netlink kernel
implementation will try to match the received vendor id
and sub command attributes with the registered ones. When
such match is found, the driver defined sub command routine
is called.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>