mtd: nand: raw: convert nand_dt_init() to ofnode_xx() interface

nand_dt_init() is still using fdtdec_xx() interface.
If OF_LIVE flag is enabled, dt property can't be get anymore.
Updating all fdtdec_xx() interface to ofnode_xx() to solve this issue.

For doing this, node parameter type must be ofnode.

First idea was to convert "node" parameter to ofnode type inside
nand_dt_init() using offset_to_ofnode(node). But offset_to_ofnode()
is not bijective, in case OF_LIVE flag is enabled, it performs an assert().

So, this leads to update nand_chip struct flash_node field from int to
ofnode and to update all nand_dt_init() callers.

Signed-off-by: Patrice Chotard <patrice.chotard@foss.st.com>
diff --git a/drivers/mtd/nand/raw/mxs_nand.c b/drivers/mtd/nand/raw/mxs_nand.c
index e6bbfac..748056a 100644
--- a/drivers/mtd/nand/raw/mxs_nand.c
+++ b/drivers/mtd/nand/raw/mxs_nand.c
@@ -1379,7 +1379,7 @@
 	nand->options |= NAND_NO_SUBPAGE_WRITE;
 
 	if (nand_info->dev)
-		nand->flash_node = dev_of_offset(nand_info->dev);
+		nand->flash_node = dev_ofnode(nand_info->dev);
 
 	nand->cmd_ctrl		= mxs_nand_cmd_ctrl;