- add a dma hack similar to the NetBSD one
- change PDQ_OS_MEM{RD,WR} to use readl/writel rather than deref'ing
a 32 bit va.
Note that I did just enough to get this working on alpha. I probably
should have updated it to use busspace, but I was too lazy to navigate
the twisty minefield of ifdefs that make up this driver.
Tested by: wilko (on both x86 and alpha)