net: spider_net: Use non-atomic bitmap API when applicable

No concurrent access is possible when a bitmap is local to a function.
So prefer the non-atomic functions to save a few cycles.
   - replace a 'for' loop by an equivalent non-atomic 'bitmap_fill()' call
   - use '__set_bit()'

While at it, clear the 'bitmask' bitmap only when needed.
Signed-off-by: Christophe JAILLET <christophe.jaillet@wanadoo.fr>
Link: https://lore.kernel.org/r/3de0792f5088f00d135c835df6c19e63ae95f5d2.1638026251.git.christophe.jaillet@wanadoo.frSigned-off-by: Jakub Kicinski <kuba@kernel.org>

drivers/net/ethernet/toshiba/spider_net.c

@@ -595,24 +595,24 @@ spider_net_set_multi(struct net_device *netdev)
 	int i;
 	u32 reg;
 	struct spider_net_card *card = netdev_priv(netdev);
-	DECLARE_BITMAP(bitmask, SPIDER_NET_MULTICAST_HASHES) = {};
+	DECLARE_BITMAP(bitmask, SPIDER_NET_MULTICAST_HASHES);
 
 	spider_net_set_promisc(card);
 
 	if (netdev->flags & IFF_ALLMULTI) {
-		for (i = 0; i < SPIDER_NET_MULTICAST_HASHES; i++) {
-			set_bit(i, bitmask);
-		}
+		bitmap_fill(bitmask, SPIDER_NET_MULTICAST_HASHES);
 		goto write_hash;
 	}
 
+	bitmap_zero(bitmask, SPIDER_NET_MULTICAST_HASHES);
+
 	/* well, we know, what the broadcast hash value is: it's xfd
 	hash = spider_net_get_multicast_hash(netdev, netdev->broadcast); */
-	set_bit(0xfd, bitmask);
+	__set_bit(0xfd, bitmask);
 
 	netdev_for_each_mc_addr(ha, netdev) {
 		hash = spider_net_get_multicast_hash(netdev, ha->addr);
-		set_bit(hash, bitmask);
+		__set_bit(hash, bitmask);
 	}
 
 write_hash: