mtd: mchp48l640: add support for Fujitsu MB85RS128TY FRAM

The Fujitsu FRAM chips use the same command set as Microchip EERAM.
The only differences are that the Fujitsu FRAM chips don't really have a
page size limit, nor do they automatically reset the WEL bit.

Signed-off-by: David Jander <david@protonic.nl>
Reviewed-by: Heiko Schocher <hs@denx.de>
Signed-off-by: Jonas Rebmann <jre@pengutronix.de>
Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>