sunxi: Add support for multiple ethadrr-esses

sunxi: Add support for multiple ethadrr-esses

Currently we fill ethaddr with a fixed unique address based on the SoCs
serial (from the sid) to make sure that boards which use the integrated
emac / gmac get a fixed mac rather then a random one.

On some boards the wifi does not come with a fixed mac either, so we need
to also set eth1addr.

This commit changes the ethaddr setting code to check for ethernet%d
aliases (as fdt_fixup_ethernet does) and set an ethaddr variable for
all present aliases.

Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>