arm64: zynqmp: Add firmware driver

[manu]

Summary

The ZynqMP SoC have a MCU running a firmware to control clocks, resets,
fpga loading etc ...
Add a driver that can be use to communicate with it.
For now only the clock and reset part are implemented.

Sponsored by: Beckhoff Automation GmbH & Co. KG

[lwhsu]

sys/dev/firmware/xilinx/zynqmp_firmware.c

3

Now we use BSD-2-Clause

Ref: rG4d846d260e2b9a3d4d0a701462568268cbfe7a5b

sys/dev/firmware/xilinx/zynqmp_firmware_if.m

3

Now we use BSD-2-Clause

Ref: rG4d846d260e2b9a3d4d0a701462568268cbfe7a5b

[manu]

Use correct SPDX identifier