[MIPS] TXx9: PCI fixes for tx3927/tx4927

* Fix tx3927 pci ops for Type-1 configuration
* Fix abort checking of tx3927 pci ops
* Flush write buffer to avoid spurious PCI error interrupt
* Add a quirk for FPCIB backplane

Signed-off-by: Atsushi Nemoto <anemo@mba.ocn.ne.jp>
Signed-off-by: Ralf Baechle <ralf@linux-mips.org>