ARM: dts: Add Raspberry Pi Compute Module 4

The Raspberry Pi Compute Module 4 (CM4) are SoMs which contain the
following:
  * BCM2711 quad core processor
  * up to 8 GB RAM
  * up to 32 GB eMMC
  * a GPIO expander
  * Gigabit PHY BCM54210PE
  * Wifi/BT module with internal and external antenna

The eMMC and the Wifi/BT module are optional.

Signed-off-by: Stefan Wahren <stefan.wahren@i2se.com>
Link: https://lore.kernel.org/r/1628334401-6577-9-git-send-email-stefan.wahren@i2se.com


Signed-off-by: Nicolas Saenz Julienne <nsaenz@kernel.org>