[SPARC64]: Fix sun4u PCI config space accesses on sun4u.

Don't provide fake PCI config space for sun4u.

Also, put back the funny host controller space handling that
at least Sabre needs.  You have to read PCI host controller
registers at their nature size otherwise you get zeros instead
of correct values.

Signed-off-by: David S. Miller <davem@davemloft.net>