After commit b3e80d44
("bonding: fix lockdep warning in bond_get_stats()") the dynamic
key is no longer necessary, as we compute nest level at run-time.
So, we can just remove it to save some lockdep key entries.

Test commands:
 ip link add bond0 type bond
 ip link add bond1 type bond
 ip link set bond0 master bond1
 ip link set bond0 nomaster
 ip link set bond1 master bond0

Reported-and-tested-by: syzbot+aaa6fa4949cc5d9b7b25@syzkaller.appspotmail.com
Cc: Dmitry Vyukov <dvyukov@google.com>
Acked-by: NTaehee Yoo <ap420073@gmail.com>
Signed-off-by: NCong Wang <xiyou.wangcong@gmail.com>
Signed-off-by: NDavid S. Miller <davem@davemloft.net>