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: Jacob Keller <jacob.e.keller@intel.com>
Reviewed-by: Jesse Brandeburg <jesse.brandeburg@intel.com>
Acked-by: Jakub Kicinski <kuba@kernel.org>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>