[SCSI] aic79xx: fix up transport settings

There's a slight problem in the way you've done the transport
parameters; reading from the variables actually produces the current
settings, not the ones you just set (and there's usually a lag because
devices don't renegotiate until the next command goes over the bus).  If
you set the bit immediately, you get into the situation where the
transport parameters report something as being set even if the drive
cannot support it.

I patched the driver to do it this way and also corrected a panic in the
proc routines.

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