This patch adds the device tree to support Toradex Apalis iMX8 [1] aka
QuadMax a computer on module which can be used on different carrier
boards.

The module consists of an NXP i.MX 8 family SoC (either i.MX 8QuadMax or
8QuadPlus), two PF8100 PMICs, a KSZ9131 Gigabit Ethernet PHY, 2, 4 or 8
GB of LPDDR4 RAM, an eMMC, an SGTL5000 analogue audio codec, an USB3503A
USB HSIC hub, an optional I2C EEPROM plus an optional Bluetooth/Wi-Fi
module.

Anything that is not self-contained on the module is disabled by
default.

The carrier board device trees in the next patch will include the
module's device tree and enable the supported peripherals of the
carrier board.

Some level of display functionality just landed upstream but requires
further integration/testing on our side. Therefore, currently only
basic console UART, eMMC and Ethernet functionality work fine.

As there is no i.MX 8QuadPlus device tree upstream those have been
dropped. However, apart from an error message during boot about it
failing to bring up the second Cortex-A72 core this boots fine on
QuadPlus' as well.

[1] https://www.toradex.com/computer-on-modules/apalis-arm-family/nxp-imx-8Signed-off-by: Marcel Ziswiler <marcel.ziswiler@toradex.com>
Signed-off-by: Shawn Guo <shawnguo@kernel.org>