drivers/spi/spi_flash: introduce common spi_flash_part_id object

To further drive to a common approach for describing the spi flash
parts in the drivers add spi_flash_part_id object. All the drivers
are updated to utilize the new object. Additionally, the driver_private
is also not needed in the spi_flash object.

A Chrome OS build of Aleena provides 960 byte saving of text. A subsequent
patch will save more memory.

Change-Id: I9c0cc75f188ac004ab647805b9551bf06a0c646b
Signed-off-by: Aaron Durbin <adurbin@chromium.org>
Reviewed-on: https://review.coreboot.org/c/coreboot/+/38378
Tested-by: build bot (Jenkins) <no-reply@coreboot.org>
Reviewed-by: Julius Werner <jwerner@chromium.org>

src/include/spi_flash.h

@@ -113,7 +113,6 @@ struct spi_flash {
 	const struct spi_flash_ops *ops;
 	/* If !NULL all protection callbacks exist. */
 	const struct spi_flash_protection_ops *prot_ops;
-	const void *driver_private;
 };
 
 void lb_spi_flash(struct lb_header *header);