MFC: 1.15; 1.16
MFC: 1.15; 1.16

- Remove unused softc.
- Use the actual clock frequency of the PCI bus instead of assuming
  33MHz for calculating the latency timer values for its children.
  Inspired by NetBSD doing the same and Linux as well as OpenSolaris
  using a similar approach.
  While at it rename a variable and change its type to be more
  appropriate fuer values of PCI properties so the variable can be
  more easily reused.
- Initialize the cache line size register of PCI devices to a
  legal value; the cache line size is limited to 64 bytes by the
  Fireplane/Safari, JBus and UPA interconnection busses. Setting
  it to an unsupported value caused bad performance at least with
  GEM as it causes them to not do cache line bursts and to not
  issue cache line commands on the PCI bus.

jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase,jrobhoward/SCADAbase