staging: nvec: Do not print free message for tx_scratch

The scratch area is not part of the pool and thus gets
no allocation message. Printing a free message would
be confusing, and the pointer subtraction would be
undefined behavior.
Signed-off-by: Julian Andres Klode <jak@jak-linux.org>
Acked-by: Marc Dietrich <marvin24@gmx.de>
Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>

drivers/staging/nvec/nvec.c

@@ -110,7 +110,8 @@ static struct nvec_msg *nvec_msg_alloc(struct nvec_chip *nvec)
 
 static void nvec_msg_free(struct nvec_chip *nvec, struct nvec_msg *msg)
 {
-	dev_vdbg(nvec->dev, "INFO: Free %ti\n", msg - nvec->msg_pool);
+	if (msg != &nvec->tx_scratch)
+		dev_vdbg(nvec->dev, "INFO: Free %ti\n", msg - nvec->msg_pool);
 	atomic_set(&msg->used, 0);
 }