[PATCH] ppc32: fix PQ2 PCI DMA interrupt handling

The bit position in the status register corresponding to the
PCI DMA interrupt was incorrect.  Additionally, we did not
have a define for the PCI DMA interrupt.

Signed-off-by: Kumar Gala <galak@kernel.crashing.org>
Signed-off-by: Paul Mackerras <paulus@samba.org>