arm: baltos: use device tree alias to access Ethernet slave

The full path has changed in the recent kernels so that it is
not possible to load them. Aliases "ethernet0" and "ethernet1"
are still present in both legacy and new kernels.

Also, fix error messages to correspond to the taken actions.

Signed-off-by: Yegor Yefremov <yegorslists@googlemail.com>