Add cpp definitions for the DMA control register fields needed for
5703/5704 configuration on PCI-X.
Add softc copy of internal"local control" register clobbered by reset.
Written by Bill Paul for FreeBSD. This port started out with the
port done to OpenBSD by nate@openbsd.org, but ended up looking much
more like the port of the ti driver done by drochner@netbsd.org
(they are similar in structure).