mtd: Uninline mtd_write_oob and move it to mtdcore.c

There's no reason for having mtd_write_oob inlined in mtd.h header.
Move it to mtdcore.c where it belongs.

Signed-off-by: Ezequiel Garcia <ezequiel@vanguardiasur.com.ar>
Acked-by: Boris Brezillon <boris.brezillon@free-electrons.com>
Signed-off-by: Jacek Anaszewski <j.anaszewski@samsung.com>

drivers/mtd/mtdcore.c

@@ -997,6 +997,18 @@ int mtd_read_oob(struct mtd_info *mtd, loff_t from, struct mtd_oob_ops *ops)
 }
 EXPORT_SYMBOL_GPL(mtd_read_oob);
 
+int mtd_write_oob(struct mtd_info *mtd, loff_t to,
+				struct mtd_oob_ops *ops)
+{
+	ops->retlen = ops->oobretlen = 0;
+	if (!mtd->_write_oob)
+		return -EOPNOTSUPP;
+	if (!(mtd->flags & MTD_WRITEABLE))
+		return -EROFS;
+	return mtd->_write_oob(mtd, to, ops);
+}
+EXPORT_SYMBOL_GPL(mtd_write_oob);
+
 /*
  * Method to access the protection register area, present in some flash
  * devices. The user data is one time programmable but the factory data is read