devlink: add value check to devlink_info_version_put()

Prevent from proceeding if there's nothing to print.

Suggested-by: Przemek Kitszel <przemyslaw.kitszel@intel.com>
Reviewed-by: Jiri Pirko <jiri@nvidia.com>
Reviewed-by: Kalesh AP <kalesh-anakkur.purayil@broadcom.com>
Tested-by: Bharath R <bharath.r@intel.com>
Signed-off-by: Jedrzej Jagielski <jedrzej.jagielski@intel.com>
Signed-off-by: Tony Nguyen <anthony.l.nguyen@intel.com>