devlink: Change devlink health locking mechanism

The devlink health reporters create/destroy and user commands currently
use the devlink->lock as a locking mechanism. Different reporters have
different rules in the driver and are being created/destroyed during
different stages of driver load/unload/running. So during execution of a
reporter recover the flow can go through another reporter's destroy and
create. Such flow leads to deadlock trying to lock a mutex already
held.

With the new locking mechanism the different reporters share mutex lock
only to protect access to shared reporters list.
Added refcount per reporter, to protect the reporters from destroy while
being used.

Signed-off-by: Moshe Shemesh <moshe@mellanox.com>
Signed-off-by: Jiri Pirko <jiri@mellanox.com>
Acked-by: Jakub Kicinski <jakub.kicinski@netronome.com>
Signed-off-by: David S. Miller <davem@davemloft.net>