arm64: mvebu: Add basic support for the Marvell Armada 7K/8K SoC

arm64: mvebu: Add basic support for the Marvell Armada 7K/8K SoC

Compared to the Armada 3700, the Armada 7K and 8K are much more on the
high-end side: they use a dual Cortex-A72 or a quad Cortex-A72, as
opposed to the Cortex-A53 for the Armada 3700.

The Armada 7K and 8K also use a fairly unique architecture, internally
they are composed of several components:

- One AP (Application Processor), which contains the processor itself
  and a few core hardware blocks. The AP used in the Armada 7K and 8K
  is called AP806, and is available in two configurations:
  dual Cortex-A72 and quad Cortex-A72.
- One or two CP (Communication Processor), which contain most of the I/O
  interfaces (SATA, PCIe, Ethernet, etc.). The 7K family chips have one
  CP, while the 8K family chips integrate two CPs, providing two times
  the number of I/O interfaces available in the CP.
  The CP used in the 7K and 8K is called CP110.

All in all, this gives the following combinations:

- Armada 7020, which is a dual Cortex-A72 with one CP
- Armada 7040, which is a quad Cortex-A72 with one CP
- Armada 8020, which is a dual Cortex-A72 with two CPs
- Armada 8040, which is a quad Cortex-A72 with two CPs

This patch adds basic support for this ARMv8 based SoC into U-Boot.
Future patches will integrate other device drivers and board support,
starting with the Marvell DB-88F7040 development board.

Signed-off-by: Stefan Roese <sr@denx.de>
Cc: Nadav Haklai <nadavh@marvell.com>
Cc: Neta Zur Hershkovits <neta@marvell.com>
Cc: Kostya Porotchkin <kostap@marvell.com>
Cc: Omri Itach <omrii@marvell.com>
Cc: Igal Liberman <igall@marvell.com>
Cc: Haim Boot <hayim@marvell.com>
Cc: Hanna Hawa <hannah@marvell.com>