SCSI_DELAY cleanup

[Warner Losh]

> also at some locations in the code SCSI_DELAY is being set to 15000. i believe
> this is the case when certain drivers (cam, ahb, aha) get loaded as a kernel
> module, but i'm not sure. it looks like this:
> 
> .if !defined(KERNBUILDDIR)
> opt_scsi.h:
> 	echo "#define SCSI_DELAY 15000" > ${.TARGET}
> .endif

These likely are hold-overs from ancient days where the default was
15s...  I'd be surprised if aha still even worked, but I have no way
to test it easily these days: I have the cards but no active systems
with ISA slots.  ahb never was my baby, but my only EISA system has
been off for at least 4 years now, and likely won't be turned back on
ever...

But regardless, neither of these controllers references SCSI_DELAY.

Cam likely can remove it safely as well, but I'd be more leery of
doing it there since I'm chicken :)

Warner