net: Rename and cleanup sunxi (Allwinner) emac driver

There have been 3 versions of the sunxi_emac support patch during its
development. Somehow version 2 ended up in upstream u-boot where as
the u-boot-sunxi git repo got version 3.

This bumps the version in upstream u-boot to version 3 of the patch:
- Initialize MII clock earlier so mii access to allow independent use
- Name change from WEMAC to EMAC to match mainline kernel & chip manual
- Cosmetic code cleanup

Signed-off-by: Stefan Roese <sr@denx.de>
Signed-off-by: Henrik Nordstrom <henrik@henriknordstrom.net>
Signed-off-by: Oliver Schinagl <oliver@schinagl.nl>
Signed-off-by: Hans de Goede <hdegoede@redhat.com>
Acked-by: Ian Campbell <ijc@hellion.org.uk>