mtd: Few follow up cleanups for Smartmedia/xD support

* Test results of few functions that were declared with __must_check
* Fix bogus gcc warning about uinitialized variable 'ret'
* Remove unused variable from mtdblock_remove_dev
* Don't use deprecated DMA_32BIT_MASK

Signed-off-by: Maxim Levitsky <maximlevitsky@gmail.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtd_blkdevs.c b/drivers/mtd/mtd_blkdevs.c
index 9dd23d6..e32c49c 100644
--- a/drivers/mtd/mtd_blkdevs.c
+++ b/drivers/mtd/mtd_blkdevs.c
@@ -380,9 +380,11 @@
 
 	add_disk(gd);
 
-	if (new->disk_attributes)
-		sysfs_create_group(&disk_to_dev(gd)->kobj,
+	if (new->disk_attributes) {
+		ret = sysfs_create_group(&disk_to_dev(gd)->kobj,
 					new->disk_attributes);
+		WARN_ON(ret);
+	}
 	return 0;
 error4:
 	module_put(tr->owner);