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>

include/linux/mtd/spi-nor.h

@@ -258,11 +258,13 @@ struct flash_info;
 /*
  * TODO: Remove, once all users of spi_flash interface are moved to MTD
  *
- * struct spi_flash {
+struct spi_flash {
  *	Defined below (keep this text to enable searching for spi_flash decl)
  * }
  */
+#ifndef DT_PLATDATA_C
 #define spi_flash spi_nor
+#endif
 
 /**
  * struct spi_nor - Structure for defining a the SPI NOR layer