hw/arm/imx8mp-evk: Remove unimplemented cpu-idle-states properties from devicetree

hw/arm/imx8mp-evk: Remove unimplemented cpu-idle-states properties from devicetree

The cpu-idle-states property causes a hard boot hang. Rather than documenting
the workaround, perform the removal from the devicetree automatically.

Signed-off-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Bernhard Beschow <shentey@gmail.com>
[Bernhard: split patch, update documentation, adapt commit message]
Signed-off-by: Bernhard Beschow <shentey@gmail.com>
Message-ID: <20250405214900.7114-3-shentey@gmail.com>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>