xtensa: ISS: fix locking in TAP network adapter

xtensa: ISS: fix locking in TAP network adapter

commit 24e94454c8cb6a13634f5a2f5a01da53a546a58d upstream.

- don't lock lp->lock in the iss_net_timer for the call of iss_net_poll,
  it will lock it itself;
- invert order of lp->lock and opened_lock acquisition in the
  iss_net_open to make it consistent with iss_net_poll;
- replace spin_lock with spin_lock_bh when acquiring locks used in
  iss_net_timer from non-atomic context;
- replace spin_lock_irqsave with spin_lock_bh in the iss_net_start_xmit
  as the driver doesn't use lp->lock in the hard IRQ context;
- replace __SPIN_LOCK_UNLOCKED(lp.lock) with spin_lock_init, otherwise
  lockdep is unhappy about using non-static key.

Signed-off-by: Max Filippov <jcmvbkbc@gmail.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>