Add board file for Meraki Z3/Z3C router
Board file was extracted from the latest Meraki firmware
for this device (mid 2025).
board.json:
```
[
{
"names": ["bus=ahb,bmi-chip-id=0,bmi-board-id=20,variant=Meraki-Z3"],
"data": "board-data/boardData_1_0_IPQ4019_DK04_2G_Z3.bin"
},
{
"names": ["bus=ahb,bmi-chip-id=0,bmi-board-id=21,variant=Meraki-Z3"],
"data": "board-data/boardData_1_0_IPQ4019_DK04_5G_Z3.bin"
}
]
```
Signed-off-by: Hal Martin <[email protected]>
Link: https://github.com/openwrt/firmware_qca-wireless/pull/111
Signed-off-by: Robert Marko <[email protected]>