hw/arm: Add GMAC devices to NPCM8XX SoC

hw/arm: Add GMAC devices to NPCM8XX SoC

The GMAC was originally created for the 8xx machine. During upstreaming
both the GMAC and the 8XX we removed it so they would not depend on each
other for the process, that connection should be added back in.

Signed-off-by: Hao Wu <wuhaotsh@google.com>
Signed-off-by: Nabih Estefan <nabihestefan@google.com>
Message-id: 20250508220718.735415-2-nabihestefan@google.com
Reviewed-by: Tyrone Ting <kfting@nuvoton.com>
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>