NFC: The core part should generate the target index

The target index can be used by userspace to uniquely identify a target
and thus should be kept unique, per NFC adapter. Moreover, some protocols
do not provide a logical index when discovering new targets, so we have to
generate one for them.
For NCI or pn533 to fetch their logical index, we added a logical_idx field
to the target structure.

Signed-off-by: Samuel Ortiz <sameo@linux.intel.com>
Signed-off-by: John W. Linville <linville@tuxdriver.com>
diff --git a/net/nfc/rawsock.c b/net/nfc/rawsock.c
index 5a839ce..b2825aa 100644
--- a/net/nfc/rawsock.c
+++ b/net/nfc/rawsock.c
@@ -92,6 +92,12 @@
 		goto error;
 	}
 
+	if (addr->target_idx > dev->target_idx - 1 ||
+	    addr->target_idx < dev->target_idx - dev->n_targets) {
+		rc = -EINVAL;
+		goto error;
+	}
+
 	rc = nfc_activate_target(dev, addr->target_idx, addr->nfc_protocol);
 	if (rc)
 		goto put_dev;