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/include/linux/mtd/mtd.h b/include/linux/mtd/mtd.h
index 6c91ba5..0893707 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -427,12 +427,15 @@
 
 static inline int mtd_suspend(struct mtd_info *mtd)
 {
+	if (!mtd->suspend)
+		return -EOPNOTSUPP;
 	return mtd->suspend(mtd);
 }
 
 static inline void mtd_resume(struct mtd_info *mtd)
 {
-	mtd->resume(mtd);
+	if (mtd->resume)
+		mtd->resume(mtd);
 }
 
 static inline int mtd_block_isbad(struct mtd_info *mtd, loff_t ofs)