sata_via: fix resource-managed iomap conversion

Conversion to resource-managed iomap was buggy causing init failures
on both vt6420 and 6421 - BAR5 wasn't mapped for both controllers
while on vt6420 sata_via tried to map BAR0-4 twice.  Fix it.

Signed-off-by: Tejun Heo <htejun@gmail.com>
Signed-off-by: Jeff Garzik <jeff@garzik.org>