mvebu: backport DTS changes for Turris Omnia from mvebu/dt

mvebu: backport DTS changes for Turris Omnia from mvebu/dt

My commit backported patches from the following links:
- https://lore.kernel.org/linux-arm-kernel/20220704113622.18887-1-kabel@kernel.org/
- https://lore.kernel.org/linux-arm-kernel/20220704113622.18887-2-kabel@kernel.org/

According to the links, they are applied in repository mvebu in branch dt,
so it should be included in upcoming Linux version soon.

Signed-off-by: Josef Schlehofer <pepe.schlehofer@gmail.com>
(cherry picked from commit 2ae26f523e9bfcd3bdfa93604afe8de9addf5a90)