net-sysfs: convert dev->operstate reads to lockless ones

[ Upstream commit 004d1383

 ]

operstate_show() can omit dev_base_lock acquisition only
to read dev->operstate.

Annotate accesses to dev->operstate.

Writers still acquire dev_base_lock for mutual exclusion.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 4893b8b3

 ("hsr: Simplify code for announcing HSR nodes timer setup")
Signed-off-by: Sasha Levin <sashal@kernel.org>