via82cxxx: workaround h/w bugs

Add custom struct ide_tp_ops instance to fix the internal bug of some VIA
chipsets which will reset the device register after changing the nIEN bit
in the device control register.

Based on commit bfce5e0 for pata_via host driver.

Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>