sunxi: Disable sun8i emac driver

Disable the sun8i emac driver for now, there are 2 issues with it:

1) It is causing issues with network connectivity under the kernel driver,
when booting the kernel with v2 of Corentin's sun8i-h3 emac driver, I get
the connection status bouncing between connected at 100mbps full-duplex
and being down every second.

The second issue is that when trying to use it from u-boot
I get a number of unaligned cache flush errors:

=> dhcp
BOOTP broadcast 1
BOOTP broadcast 2
CACHE: Misaligned operation at range [7bf594a8, 7bf59628]
BOOTP broadcast 3
CACHE: Misaligned operation at range [7bf59c90, 7bf59e10]
CACHE: Misaligned operation at range [7bf5a478, 7bf5a5f8]
DHCP client bound to address 10.42.43.80 (1009 ms)

Cc: Chen-Yu Tsai <wens@csie.org>
Cc: Corentin LABBE <clabbe.montjoie@gmail.com>
Cc: Amit Singh Tomar <amittomer25@gmail.com>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>