devlink: protect devlink param list by instance lock

Commit 1d18bb1a ("devlink: allow registering parameters after
the instance") as the subject implies introduced possibility to register
devlink params even for already registered devlink instance. This is a
bit problematic, as the consistency or params list was originally
secured by the fact it is static during devlink lifetime. So in order to
protect the params list, take devlink instance lock during the params
operations. Introduce unlocked function variants and use them in drivers
in locked context. Put lock assertions to appropriate places.

Signed-off-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Jakub Kicinski <kuba@kernel.org>
Reviewed-by: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Ido Schimmel <idosch@nvidia.com>
Reviewed-by: Simon Horman <simon.horman@corigine.com>
Tested-by: Simon Horman <simon.horman@corigine.com>
Signed-off-by: David S. Miller <davem@davemloft.net>