Export a unique board identifier using "board.id" for devlink's
.info_get command.

Obtain this by reading the NVM for the PBA identification string.
Signed-off-by: NJacob Keller <jacob.e.keller@intel.com>
Reviewed-by: NJesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: NJakub Kicinski <kuba@kernel.org>
Tested-by: NAndrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: NJeff Kirsher <jeffrey.t.kirsher@intel.com>