mmc: card: Prevent partition scan for the eMMC boot areas

It seems very unlikely that eMMC devices would hold a standard
partitiontable in one of it's boot areas. Therefore, let's prevent
them from being scanned.
Signed-off-by: NUlf Hansson <ulf.hansson@linaro.org>

drivers/mmc/card/block.c

@@ -2136,7 +2136,7 @@ static struct mmc_blk_data *mmc_blk_alloc_req(struct mmc_card *card,
 	md->disk->queue = md->queue.queue;
 	md->disk->driverfs_dev = parent;
 	set_disk_ro(md->disk, md->read_only || default_ro);
-	if (area_type & MMC_BLK_DATA_AREA_RPMB)
+	if (area_type & (MMC_BLK_DATA_AREA_RPMB | MMC_BLK_DATA_AREA_BOOT))
 		md->disk->flags |= GENHD_FL_NO_PART_SCAN;
 
 	/*