mtd: do not use mtd->suspend and mtd->resume directly

Just call the 'mtd_suspend()' and 'mtd_resume()' - they will do nothing
if the operation is not defined.

Signed-off-by: Artem Bityutskiy <artem.bityutskiy@linux.intel.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/drivers/mtd/mtdcore.c b/drivers/mtd/mtdcore.c
index 66494ee..6ae9ca0 100644
--- a/drivers/mtd/mtdcore.c
+++ b/drivers/mtd/mtdcore.c
@@ -119,10 +119,7 @@
 {
 	struct mtd_info *mtd = dev_get_drvdata(dev);
 
-	if (mtd && mtd->suspend)
-		return mtd_suspend(mtd);
-	else
-		return 0;
+	return mtd_suspend(mtd);
 }
 
 static int mtd_cls_resume(struct device *dev)