aic7xxx: convert to SPI transport class Domain Validation

Now that we export all the parameters, this is easy to do.
It also means that we can dump about 2000 lines of code that
were dedicated to doing this internally.

Additionally, this removes all the aic7xxx driver abuse
of SCSI timers which were embedded in the DV routines.

Signed-off-by: James Bottomley <James.Bottomley@SteelEye.com>