mx6cuboxi: Do not print devicetree model

mx6cuboxi: Do not print devicetree model

The mx6cuboxi_defconfig target supports several board
variants. All of these variants use the hummingboard devicetree in U-Boot.

Currently, the devicetree model as well as the board variant name
are shown:

...
Model: SolidRun HummingBoard2 Dual/Quad (1.5som+emmc)
Board: MX6 Cubox-i
...

Printing the devicetree model that is used internally by U-Boot
may confuse users.

Unselect the CONFIG_DISPLAY_BOARDINFO option so that only the
board name is printed in board_late_init() instead.

Signed-off-by: Fabio Estevam <festevam@gmail.com>
Tested-by: Christian Gmeiner <cgmeiner@igalia.com>