machine: add the F7008-2.5 (GPOE-V1.2) 8+1 target

Add support for the F7008-2.5 board (PCB F7008-2.5GPOE-V1.2), an
RTL8373N + RTL8224N design with eight 2.5GBASE-T ports and one SFP+ cage.

The LED pads are not wired in port order, so the generic DEFAULT_8C_1SFP
target lights the wrong lamp on this board. The pad to lamp map was
measured on the hardware and is documented in doc/devices/F7008-2.5.md.

The green lamp marks a 2.5G link, the yellow lamp blinks while data flows.

doc/supported_devices.md

@@ -36,6 +36,7 @@ The following devices have been tested and are fully working:
 | Xikestore| SKS3200M-4GPY2XF| Yes     | [SWTG024AS-v1.0](devices/SWTG024AS.md)                                    |       | 4 + 2 |
 | XikeStor | SKS3200-8E1X    | Yes     | [SWTG118AS-V2.1-17462](devices/SWTGW218AS.md)                             | 2M    | 8 + 1 |
 | Ztyuav   | Z-QWYT0402      | No      | [PCB-K0402WS-V3.0](devices/PCB-K0402WS-V3.0.md)                           |       | 4 + 2 |
+| Guangnianwei | 7018-2.5G   | No      | [F7008-2.5GPOE-V1.2](devices/F7008-2.5.md)                                | 8M    | 8 + 1 |
 
 For KP-9000-6XH-X2 / KP-9000-6XHML-X2 / Mokerlink 2G040210GSM devices, select
 the machine target by PCB revision. The ML/non-ML or managed/unmanaged label