bnxt_en: Add partno to devlink info_get cb

Add part number info from the vital product data to info_get command
via devlink tool. Update bnxt.rst documentation as well.

Cc: Jakub Kicinski <[e-mail]>
Signed-off-by: Vasundhara Volam <[e-mail]>
Signed-off-by: Michael Chan <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

Documentation/networking/devlink/bnxt.rst

···
    * - Name
      - Type
      - Description
+   * - ``board.id``
+     - fixed
+     - Part number identifying the board design
    * - ``asic.id``
      - fixed
      - ASIC design identifier

drivers/net/ethernet/broadcom/bnxt/bnxt_devlink.c

···
 	if (rc)
 		return rc;
 
+	if (strlen(bp->board_partno)) {
+		rc = devlink_info_version_fixed_put(req,
+			DEVLINK_INFO_VERSION_GENERIC_BOARD_ID,
+			bp->board_partno);
+		if (rc)
+			return rc;
+	}
+
 	sprintf(buf, "%X", bp->chip_num);
 	rc = devlink_info_version_fixed_put(req,
 			DEVLINK_INFO_VERSION_GENERIC_ASIC_ID, buf);