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 <edumazet@google.com>
Link: https://lore.kernel.org/r/20220203064609.3242863-1-eric.dumazet@gmail.com


Signed-off-by: Jakub Kicinski <kuba@kernel.org>