mtd: move mtd_read_oob() definition out of mtd.h

mtd_read_oob() will be expanded a little, so don't leave it in the header
as a static inline function.

Signed-off-by: Brian Norris <computersforpeace@gmail.com>
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 63dadc0..81d61e7 100644
--- a/include/linux/mtd/mtd.h
+++ b/include/linux/mtd/mtd.h
@@ -265,14 +265,7 @@
 int mtd_panic_write(struct mtd_info *mtd, loff_t to, size_t len, size_t *retlen,
 		    const u_char *buf);
 
-static inline int mtd_read_oob(struct mtd_info *mtd, loff_t from,
-			       struct mtd_oob_ops *ops)
-{
-	ops->retlen = ops->oobretlen = 0;
-	if (!mtd->_read_oob)
-		return -EOPNOTSUPP;
-	return mtd->_read_oob(mtd, from, ops);
-}
+int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops);
 
 static inline int mtd_write_oob(struct mtd_info *mtd, loff_t to,
 				struct mtd_oob_ops *ops)