net: minor __dev_alloc_name() optimization

__dev_alloc_name() allocates a private zeroed page,
then sets bits in it while iterating through net devices.

It can use __set_bit() to avoid unnecessary locked operations.

Signed-off-by: Eric Dumazet <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Jakub Kicinski <[e-mail]>

net/core/dev.c

···
 				/*  avoid cases where sscanf is not exact inverse of printf */
 				snprintf(buf, IFNAMSIZ, name, i);
 				if (!strncmp(buf, name_node->name, IFNAMSIZ))
-					set_bit(i, inuse);
+					__set_bit(i, inuse);
 			}
 			if (!sscanf(d->name, name, &i))
 				continue;
···
 			/*  avoid cases where sscanf is not exact inverse of printf */
 			snprintf(buf, IFNAMSIZ, name, i);
 			if (!strncmp(buf, d->name, IFNAMSIZ))
-				set_bit(i, inuse);
+				__set_bit(i, inuse);
 		}
 
 		i = find_first_zero_bit(inuse, max_netdevices);