mv643xx_eth: reverse topological sort of functions

This patch performs a reverse topological sort of all functions in
mv643xx_eth.c, so that we can get rid of all forward declarations,
and end up with a more understandable driver due to related functions
being grouped together.
Signed-off-by: NLennert Buytenhek <buytenh@marvell.com>
Acked-by: NDale Farnsworth <dale@farnsworth.org>