pata_via: add VX800 flag; add function for fixing h/w bugs

Add flag VIA_SATA_PATA for vx800, VX800 uses the same
chipset(0x0581/0x5324) as CX700, which has 1 PATA channel(Master/Slave)
and 1 SATA channel(Master/Slave) Add function <via_ata_tf_load>.  This is
to fix the internal bug of VIA chipsets, which will reset the device
register after changing the IEN bit in CTL register

Signed-off-by: Joseph Chan <josephchan@via.com.tw>
Cc: Tejun Heo <tj@kernel.org>
Cc: Alan Cox <alan@lxorguk.ukuu.org.uk>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Jeff Garzik <jgarzik@redhat.com>