mtd: do not use mtd->get_unmapped_area directly

Remove direct usage of mtd->get_unmapped_area. Instead, just call
'mtd_get_unmapped_area()' which will return -EOPNOTSUPP if the function
is not implemented and test for this error code.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtdconcat.c b/drivers/mtd/mtdconcat.c
index f694b51..9119f76 100644
--- a/drivers/mtd/mtdconcat.c
+++ b/drivers/mtd/mtdconcat.c
@@ -726,11 +726,7 @@
 		if (offset + len > subdev->size)
 			return (unsigned long) -EINVAL;
 
-		if (subdev->get_unmapped_area)
-			return mtd_get_unmapped_area(subdev, len, offset,
-						     flags);
-
-		break;
+		return mtd_get_unmapped_area(subdev, len, offset, flags);
 	}
 
 	return (unsigned long) -ENOSYS;