spi: Tweak a few strange SPI NOR features for of-platdata

The #define of one struct to another has been around for a while. It
confuses dtoc and makes it think that struct spi_flash does not exist.

Make a few changes to improve things while we wait for migration to be
completed:

- Move the 'struct spi_flash' to column 1 so dtoc scans it
- Remove the #define when compiling dt-platdata.c
- Update the strange mtd_get/set_of_node() functions
- Use struct spi_nor in the drivers, so dtoc sees the correct struct

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/drivers/mtd/spi/sf-uclass.c b/drivers/mtd/spi/sf-uclass.c
index ed629f1..3017022 100644
--- a/drivers/mtd/spi/sf-uclass.c
+++ b/drivers/mtd/spi/sf-uclass.c
@@ -100,5 +100,5 @@
 	.id		= UCLASS_SPI_FLASH,
 	.name		= "spi_flash",
 	.post_bind	= spi_flash_post_bind,
-	.per_device_auto	= sizeof(struct spi_flash),
+	.per_device_auto	= sizeof(struct spi_nor),
 };