Add support of Nallino board to U-Boot

This MR just activates the support of Nallino board in U-Boot by adjusting corresponding configs in machine layer.

Refer to https://secogroup.atlassian.net/browse/YT-212 Nallino: add U-Boot support for the description of the task.

Patches which add the support of Nallino board to U-Boot itself can be found in following MR: seco-ne/3rd-party/kuk/uboot-imx-kuk!227 (merged)

Note: there are 3 active MR groups for U-Boot right now. And although they are not dependent on each other, if one of them is merged, other two needs to be rechecked and probably updated. Here is a full list of MRs:

Santino support:

• seco-ne/3rd-party/kuk/uboot-imx-kuk!233 (merged)
• !600 (merged)

Nallino support:

• !592 (merged)
• seco-ne/3rd-party/kuk/uboot-imx-kuk!227 (merged)

FNGS corruption:

• seco-ne/3rd-party/kuk/uboot-imx-kuk!230