In drivers/ide/pci/it8172.h, it8172_ratefilter() and
init_setup_it8172() are declared and the latter is referenced
in it8172_chipsets.  Both functions are not defined or used
anywhere.  This patch removes the prototypes and reference.
it8172 should be compilable now.
Signed-off-by: Tejun Heo <tj@home-tj.org>
Signed-off-by: Bartlomiej Zolnierkiewicz <bzolnier@gmail.com>