arm64: dts: meson: Add minimal support for Odroid-N2

This patch adds basic support for :
- Amlogic G12B, which is very similar to G12A
- The HardKernel Odroid-N2 based on the S922X SoC

The Amlogic G12B SoC is very similar with the G12A SoC, sharing
most of the features and architecture, but with these differences :
- The first CPU cluster only has 2xCortex-A53 instead of 4
- G12B has a second cluster of 4xCortex-A73
- Both cluster can achieve 2GHz instead of 1,8GHz for G12A
- CPU Clock architecture is difference, thus needing a different
  compatible to handle this slight difference
- Supports a MIPI CSI input
- Embeds a Mali-G52 instead of a Mali-G31, but integration is the same

Actual support is done in the same way as for the GXM support, including
the G12A dtsi and redefining the CPU clusters.
Unlike GXM, the first cluster is different, thus needing to remove
the last 2 cpu nodes of the first cluster.

Signed-off-by: Neil Armstrong <narmstrong@baylibre.com>
Reviewed-by: Martin Blumenstingl <martin.blumenstingl@googlemail.com>
Tested-by: Anand Moon <linux.amoon@gmail.com>
[khilman: add vin-supply for vcc_v5 as suggested by Anand Moon]
Signed-off-by: Kevin Hilman <khilman@baylibre.com>