imx: ventana: enable ONFI detection to fix NAND chip configuration

Enable ONFI detection to fix NAND chip configuration. Without this
the NAND oobsize will be wrong which leads to invalid ECC strength and
incompatibility with the previous configuration.

Fixes: 777f333c ("imx: ventana: enable dm for MTD and NAND")

Signed-off-by: Tim Harvey <tharvey@gateworks.com>
Reviewed-by: Fabio Estevam <festevam@denx.de>