Some minor refactoring in the generic code was necessary for
this:
1) This controller requires 8-byte access to the interrupt map
and clear register. They are 64-bits on all the other
SBUS and PCI controllers anyways, so this was easy to cure.
2) The IMAP register has a different layout and some bits that we
need to preserve, so use a read/modify/write when making
changes to the IMAP register in generic code.
3) Flushing the entire IOMMU TLB is best done with a single write
to a register on this PCI controller, add a iommu->iommu_flushinv
for this.
Still lacks MSI support, that will come later.
Signed-off-by: David S. Miller <davem@davemloft.net>