sbc8548: update PCI/PCI-e support code

sbc8548: update PCI/PCI-e support code

The PCI/PCI-e support for the sbc8548 was based on an earlier
version of what the MPC8548CDS board was using, and in its
current state it won't even compile.  This re-syncs it to match
the latest codebase and makes use of the new shared PCI functions
to reduce board duplication.

It borrows from the MPC8568MDS, in that it pulls the PCI-e I/O
back to 0xe280_0000 (where PCI2 would be on MPC8548CDS), and
similarly it coalesces the PCI and PCI-e mem into one single TLB.

Both PCI-x and PCI-e have been tested with intel e1000 cards
under linux (with an accompanying dts change in place)

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Signed-off-by: Kumar Gala <galak@kernel.crashing.org>