ipq40xx: add label-mac-device alias for Linksys WHW01

ipq40xx: add label-mac-device alias for Linksys WHW01

Set the label-mac-device to be able to easily fetch the mac-address of
the device, which is printed on the bottom of the case.
While at it, remove the TODO - the ethernet0 alias is needed to get the
mac from bootloader.

Signed-off-by: Christoph Krapp <achterin@gmail.com>
Link: https://github.com/openwrt/openwrt/pull/20441
Signed-off-by: Robert Marko <robimarko@gmail.com>
(cherry picked from commit deca8fd24bcd039a3784bf83db5541b297def8ff)
Link: https://github.com/openwrt/openwrt/pull/20454
Signed-off-by: Hauke Mehrtens <hauke@hauke-m.de>