apm821xx: WNDAP660: fix ethernet port ordering

apm821xx: WNDAP660: fix ethernet port ordering

Tim Small reported:
| Viewing the 'Network' -> 'Switch' config page in LuCI:
|
| The LuCI LAN 1 port corresponds to the port physically
|     labelled 2 at the rear of the device.
| [...]
|
| When a patch cord is attached to the port labelled 1 [...],
| the LED labelled °2 illuminates.

=> essentially, the Ports and LEDs are reversed.

Reported-by: Tim Small
Fixes: #10111
Signed-off-by: Christian Lamparter <chunkeey@gmail.com>
(cherry picked from commit 36483600d337ab3ec8a6dabeaa160614d07f5588)