Remove ccbque.h from i386/isa.

inline ccbque.h into scsi_low.h. The file isn't MD, so shouldn't live
in i386/isa. It's only used by scsi_low, so move it there so no new
clients accidentally grow. scsi_low may not even still work, and the
locking here is still SPL based. CAM should do the right thing, but
I've received no reports of these cards still working. At least it
compiles still and there's one fewer files in sys/i386/isa. While I'm
here, ansify and de-splize. CCB_MWANTED appears to be a clear-only
flag, but I've not changed that.

Differential Review: https://reviews.freebsd.org/D13672