mtd: OneNAND: add enable / disable methods to onenand_chip

Add enable / disable methods called from get_device() / release_device().
These can be used, for example, to allow the driver to prevent the voltage
regulator from being put to sleep while OneNAND is in use.

Signed-off-by: Adrian Hunter <adrian.hunter@nokia.com>
Signed-off-by: David Woodhouse <David.Woodhouse@intel.com>
diff --git a/include/linux/mtd/onenand.h b/include/linux/mtd/onenand.h
index 6da3fe3..ae418e4 100644
--- a/include/linux/mtd/onenand.h
+++ b/include/linux/mtd/onenand.h
@@ -118,6 +118,8 @@
 	int (*chip_probe)(struct mtd_info *mtd);
 	int (*block_markbad)(struct mtd_info *mtd, loff_t ofs);
 	int (*scan_bbt)(struct mtd_info *mtd);
+	int (*enable)(struct mtd_info *mtd);
+	int (*disable)(struct mtd_info *mtd);
 
 	struct completion	complete;
 	int			irq;