[SCSI] aic7xxx: fix timer handling bug

The driver is doing a rather stupid mod_timer allegedly to "give
request sense more time to complete".  This is illegal and pointless,
so just eliminate it.  Also eliminate all the other uses of struct
timer_list in the driver, which are mostly bogus.

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