ps2: remove update_irq() function and update_arg parameter

ps2: remove update_irq() function and update_arg parameter

Now that all the PS2 devices have been converted to use GPIOs the update_irq()
callback function and the update_arg parameter can be removed.

This allows these arguments to be completely removed from ps2_kbd_init() and
ps2_mouse_init(), along with the transitional logic that was added to
ps2_raise_irq() and ps2_lower_irq().

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Acked-by: Helge Deller <deller@gmx.de>
Reviewed-by: Peter Maydell <peter.maydell@linaro.org>
Message-Id: <20220624134109.881989-55-mark.cave-ayland@ilande.co.uk>