arm64: dts: ti: Add support for phyBOARD-Electra-AM642

Add basic support for phyCORE-AM64x SoM & phyBOARD-Electra-AM642 CB.

The phyCORE-AM64x [1] is a SoM (System on Module) featuring TI's AM64x SoC.
It can be used in combination with different carrier boards.
This module can come with different sizes and models for
DDR, eMMC, SPI NOR Flash and various SoCs from the AM64x family.

A development Kit, called phyBOARD-Electra [2] is used as a carrier board
reference design around the AM64x SoM.

Supported features:
  * Debug UART
  * Heartbeat LED
  * GPIO buttons & LEDs
  * SPI NOR flash
  * eMMC
  * CAN
  * Ethernet
  * Micro SD card
  * I2C EEPROM
  * I2C RTC
  * I2C LED Dimmer
  * USB

For more details, see:

[1] Product page SoM: https://www.phytec.com/product/phycore-am64x
[2] Product page CB: https://www.phytec.com/product/phyboard-am64x



Signed-off-by: Wadim Egorov <w.egorov@phytec.de>
Reviewed-by: Ravi Gunasekaran <r-gunasekaran@ti.com>
Signed-off-by: Vignesh Raghavendra <vigneshr@ti.com>
Link: https://lore.kernel.org/r/20230104162927.1215033-2-w.egorov@phytec.de