hw/gpio: Remove MAX7310 device

hw/gpio: Remove MAX7310 device

The MAX7310 GPIO controller was used only by the XScale-based Zaurus
machine types.  Now they have been removed we can remove this device
model as well.

Because this device is an I2C device, in theory it could be created
by users on the command line for boards with a different I2c
controller, but we don't believe users are doing this -- it would be
impossible on the command line to connect up the GPIO inputs/outputs.
The only example a web search produces for "device max7310" is a user
trying to create this because they didn't realize that there was no
way to manipulate the GPIO lines.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Reviewed-by: Philippe Mathieu-Daudé <philmd@linaro.org>
Message-id: 20241003140010.1653808-3-peter.maydell@linaro.org