devlink: add forgotten devlink instance lock assertion to devl_param_driverinit_value_set()

Driver calling devl_param_driverinit_value_set() has to hold devlink
instance lock while doing that. Put an assertion there.

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>