The MR25 family doesn't support JEDEC, so they need explicit mentioning
in the list of supported spi IDs. This makes it possible to add these
using for example:

	compatible = "everspin,mr25h40";

There was already an entry for mr25h256. Move that one out of the "keep
for compatibility" section and put in a new group for Everspin MRAMs.
Signed-off-by: Uwe Kleine-König <u.kleine-koenig@pengutronix.de>
Acked-by: Rob Herring <robh@kernel.org>
Signed-off-by: Cyrille Pitchen <cyrille.pitchen@atmel.com>