[HW] TiaC SC18IS604 Arduino as Shield

[rexut]

Is this request related to a missing driver support for a particular hardware platform, SoC or board? Please describe.
I need support for our own TiaC Systems Evaluation Shield based on the NXP SC18IS604 chip as shields:

• TiaC SC18IS604 Arduino, bridge from Arduino SPI bus to a new single I2C bus, MFD driver: SC18IS604
  • I2C driver: SC18IS604 for i2c controller
  • GPIO driver: SC18IS604 for gpio controller

In this early first stage the Zephyr upstream samples "Shell on USB console" should be usable.

Describe why you are asking for this support?
With this support the board+shield variation for bus bridge based systems will scaling up.

I'm preparing a changeset for PR. I'll maintain the new board for Bridle and later contribute and maintain to/in Zephyr upstream.

Additional context
The new shields support will coming together with Arduino UNO R3 interconnection support as currently provided by Bridle only.