ide: remove no longer used au1xxx-ide driver

Commit 54ff4a1d

 ("MIPS: Alchemy: pata_platform for DB1200")
from year 2014 converted the only user of au1xxx-ide IDE host
driver (MIPS Alchemy DB1200 platform) to use pata_platform
libata host driver instead. This patch removes dead au1xxx-ide
driver code.

Acked-by: David S. Miller <davem@davemloft.net>
Acked-by: Manuel Lauss <manuel.lauss@gmail.com>
Acked-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: Thomas Bogendoerfer <tsbogend@alpha.franken.de>