devlink: convert param list to xarray

Loose the linked list for params and use xarray instead.

Note that this is required to be eventually possible to call
devl_param_driverinit_value_get() without holding instance lock.

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