uboot-phytec

cmd: mtdparts: describe as legacy

The 'mtdparts' command is not needed anymore. While the environment
variable is still valid (and useful, along with the 'mtdids' one), the
command has been replaced by 'mtd' which is much more close to the MTD
stack and do not add its own specific glue.

Signed-off-by: Miquel Raynal <miquel.raynal@bootlin.com>
Reviewed-by: Stefan Roese <sr@denx.de>
Reviewed-by: Boris Brezillon <boris.brezillon@bootlin.com>