mv643xx_eth: Remove unused register defines

Most of the register defines in drivers/net/mv643xx_eth.h aren't
used at all.  Nuke them -- we can always re-add them if/when we
need them, and meanwhile, they unnecessarily clutter up the
header file.

Signed-off-by: Lennert Buytenhek <buytenh@marvell.com>
Acked-by: Tzachi Perelstein <tzachi@marvell.com>
Signed-off-by: Dale Farnsworth <dale@farnsworth.org>