net: dsa: hellcreek: Use the bitmap API to allocate bitmaps

Use devm_bitmap_zalloc() instead of hand-writing them.

It is less verbose and it improves the semantic.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Acked-by: Kurt Kanzenbach <kurt@linutronix.de>
Link: https://lore.kernel.org/r/8306e2ae69a5d8553691f5d10a86a4390daf594b.1657376651.git.christophe.jaillet@wanadoo.frSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/dsa/hirschmann/hellcreek.c

@@ -1894,11 +1894,8 @@ static int hellcreek_probe(struct platform_device *pdev)
 		if (!port->counter_values)
 			return -ENOMEM;
 
-		port->vlan_dev_bitmap =
-			devm_kcalloc(dev,
-				     BITS_TO_LONGS(VLAN_N_VID),
-				     sizeof(unsigned long),
-				     GFP_KERNEL);
+		port->vlan_dev_bitmap = devm_bitmap_zalloc(dev, VLAN_N_VID,
+							   GFP_KERNEL);
 		if (!port->vlan_dev_bitmap)
 			return -ENOMEM;