via-ide: initialise IDE controller in legacy mode

via-ide: initialise IDE controller in legacy mode

According to both the VT82C686B and VT8231 datasheets the VIA Southbridge IDE
controller is initialised in legacy mode.

This allows Linux to correctly determine that legacy rather than PCI IRQ routing
should be used since the boot console text in the fulong2e test image changes from:

scsi0 : pata_via
scsi1 : pata_via
ata1: PATA max UDMA/100 cmd 0xffffffffbfd04050 ctl 0xffffffffbfd04062 \
  bmdma 0xffffffffbfd04040 irq 14
ata2: PATA max UDMA/100 cmd 0xffffffffbfd04058 ctl 0xffffffffbfd04066 \
  bmdma 0xffffffffbfd04048 irq 14

to:

scsi0 : pata_via
scsi1 : pata_via
ata1: PATA max UDMA/100 cmd 0xffffffffbfd001f0 ctl 0xffffffffbfd003f6 \
  bmdma 0xffffffffbfd04040 irq 14
ata2: PATA max UDMA/100 cmd 0xffffffffbfd00170 ctl 0xffffffffbfd00376 \
  bmdma 0xffffffffbfd04048 irq 15

Signed-off-by: Mark Cave-Ayland <mark.cave-ayland@ilande.co.uk>
Tested-by: BALATON Zoltan <balaton@eik.bme.hu>
Signed-off-by: BALATON Zoltan <balaton@eik.bme.hu>
Message-id: 20200313082444.2439-6-mark.cave-ayland@ilande.co.uk
Signed-off-by: John Snow <jsnow@redhat.com>