MIPS: Alchemy: move ethernet registers to ethernet driver

Move the register offsets and bit descriptions from the au1000.h header
to their only user, the au1000_eth.c driver.

Signed-off-by: Manuel Lauss <manuel.lauss@gmail.com>
Cc: netdev@vger.kernel.org
Cc: Linux-MIPS <linux-mips@linux-mips.org>
Patchwork: https://patchwork.linux-mips.org/patch/7460/


Signed-off-by: Ralf Baechle <ralf@linux-mips.org>