This patch (a) removes dead code, (b) renames some static functions with
names that are more apropriate for static functions, and (c) implements a
slave_configure() function.

With the patch I just sent to Linus (et al.) to fix the SCSI core to allow
slave_configure() to tweak (meaningfully) the two variables I need to set,
we'll be able to remove US_FL_MODE_XLATE.

(Well, actually, we also need to fix sr.c to respect the use_10_for_ms
flag, but that should be easy once the rest is done.)