arm64: mvebu: Add Armada 7K db-88f7040 development board support

This patch adds basic support for the Marvell Armada 7K DB-88F7040
development board. Supported are the following interfaces:
- UART
- SPI (incl. SPI NOR)
- I2C
- USB
- SATA / AHCI

Support for other interfaces will follow.

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>