ARM: dts: socfpga: Add support of Terasic DE0 Atlas board

The Terasic DE0 Atlas board is also known as the DE0-Nano board.
This patch adds the DTS board file for the DE0-Nano Sockit board, and not
the DE0 Nano "Development Board".

Signed-off-by: Dalon Westergreen <dwesterg@gmail.com>
Signed-off-by: Dinh Nguyen <dinguyen@opensource.altera.com>
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v3: Updated skew settings for the gmac1 node as this board is using the
    KSZ9031 PHY instead of the 9021 PHY.
v2: use stdpath-out for console and remove comment regarding u-boot ethaddr