hw/display/apple-gfx: Adds PCI implementation

hw/display/apple-gfx: Adds PCI implementation

This change wires up the PCI variant of the paravirtualised
graphics device, mainly useful for x86-64 macOS guests, implemented
by macOS's ParavirtualizedGraphics.framework. It builds on code
shared with the vmapple/mmio variant of the PVG device.

Signed-off-by: Phil Dennis-Jordan <phil@philjordan.eu>
Reviewed-by: Akihiko Odaki <akihiko.odaki@daynix.com>
Message-ID: <20241223221645.29911-4-phil@philjordan.eu>
Signed-off-by: Philippe Mathieu-Daudé <philmd@linaro.org>