Enhance speed detection

[Sean Bruno]

On Mon, 2009-02-16 at 15:57 -0800, Sean Bruno wrote:
> Synopsis:
> If speed of link between two devices is slower than the reported max
> speed of both endpoints, the current driver will fail and be unable to
> negotiate.
> 
> Summary:
> Test negotiated speed by reading the CSRROM into a dummy variable.
> If that read fails, decrement our speed and retry.  If all else fails,
> go to lowest speed possible.
> 
> Report speed to the user.
> Add display of the Bus Info Block when debug.firewire_debug > 1
> Support the Bus Info Block(1394a-2000) method of speed detection.
> 
> _______________________________________________

I also should note that I am moving "hold_count" to 0 for future
releases.

This variable determines how many bus resets to "hold" a removed
firewire device before deletion.  I don't feel this is useful and will
probably drop support for this sysctl in the future.

Sean