tsnep: Fix tsnep_request_irq() format-overflow warning

Compiler warns about a possible format-overflow in tsnep_request_irq():
drivers/net/ethernet/engleder/tsnep_main.c:884:55: warning: 'sprintf' may write a terminating nul past the end of the destination [-Wformat-overflow=]
sprintf(queue->name, "%s-rx-%d", name,
^
drivers/net/ethernet/engleder/tsnep_main.c:881:55: warning: 'sprintf' may write a terminating nul past the end of the destination [-Wformat-overflow=]
sprintf(queue->name, "%s-tx-%d", name,
^
drivers/net/ethernet/engleder/tsnep_main.c:878:49: warning: '-txrx-' directive writing 6 bytes into a region of size between 5 and 25 [-Wformat-overflow=]
sprintf(queue->name, "%s-txrx-%d", name,
^~~~~~

Actually overflow cannot happen. Name is limited to IFNAMSIZ, because
netdev_name() is called during ndo_open(). queue_index is single char,
because less than 10 queues are supported.

Fix warning with snprintf(). Additionally increase buffer to 32 bytes,
because those 7 additional bytes were unused anyway.

Reported-by: kernel test robot <[e-mail]>
Closes: https://lore.kernel.org/oe-kbuild-all/[e-mail]/
Signed-off-by: Gerhard Engleder <[e-mail]>
Reviewed-by: Jacob Keller <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

drivers/net/ethernet/engleder/tsnep.h

···
 
 struct tsnep_queue {
 	struct tsnep_adapter *adapter;
-	char name[IFNAMSIZ + 9];
+	char name[IFNAMSIZ + 16];
 
 	struct tsnep_tx *tx;
 	struct tsnep_rx *rx;

drivers/net/ethernet/engleder/tsnep_main.c

···
 		dev = queue->adapter;
 	} else {
 		if (queue->tx && queue->rx)
-			sprintf(queue->name, "%s-txrx-%d", name,
-				queue->rx->queue_index);
+			snprintf(queue->name, sizeof(queue->name), "%s-txrx-%d",
+				 name, queue->rx->queue_index);
 		else if (queue->tx)
-			sprintf(queue->name, "%s-tx-%d", name,
-				queue->tx->queue_index);
+			snprintf(queue->name, sizeof(queue->name), "%s-tx-%d",
+				 name, queue->tx->queue_index);
 		else
-			sprintf(queue->name, "%s-rx-%d", name,
-				queue->rx->queue_index);
+			snprintf(queue->name, sizeof(queue->name), "%s-rx-%d",
+				 name, queue->rx->queue_index);
 		handler = tsnep_irq_txrx;
 		dev = queue;
 	}