ath79: Forward port support for CR3000

ath79: Forward port support for CR3000

The PowerCloud Systems CR3000 was a cloud-managed CPE for a now defunct
NaaS offering.  It was previously supported under the ar71xx branch and
this forward ports that support with some notable differences:

1) Since reverting to stock firmware is now irrelevant there is is only
a single openwrt image generated which uses the entire flash rather than
preserving PowerCloud-specific partitions that are unneeded to openwrt--
those partitions will be erased and used by the openwrt image.

2) Rather than use a non-standard probe order for the ethernet devices,
this image uses a set of 'ip link set ethX name ethY' commands very early
in preinit (before the network is used at all), in order to have the the
switch and Wan use the same ethernet names as in previous images.

3) /etc/config/wireless will need to be regenerated as the path to the
wireless device has changed due to differences in ath79 DT for ar93x
compared to ar71xx images.

4) eth0 is wan and eth1 is lan (switch)

Signed-off-by: Daniel F. Dickinson <cshored@thecshore.com>