net: eth-uclass: Change uclass driver name to ethernet

dev_read_alias_seq() used uc_drv->name compared to alias
stem string, Ethernet's alias stem uses "ethernet", which
does not match the eth-uclass driver name "eth", can not
get the correct index of ethernet alias namer. So it seems
change uclass driver name to match the alias stem is a more
reasonable way.

Signed-off-by: David Wu <david.wu@rock-chips.com>
Reviewed-by: Simon Glass <sjg@chromium.org>