mv643xx_eth: get rid of ETH_/ethernet_/eth_ prefixes

The fact that mv643xx_eth is an ethernet driver is pretty obvious,
and having a lot of internal-use-only functions and defines prefixed
with ETH_/ethernet_/eth_ prefixes is rather pointless.  So, get rid
of most of those prefixes.
Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Dale Farnsworth <dale@farnsworth.org>