Drop function declarations at the beginning of the file scrub.c. These
functions are defined before they are used in the same file and don't
need forward declaration.

No functional changes.
Reviewed-by: NJohannes Thumshirn <johannes.thumshirn@wdc.com>
Signed-off-by: NAnand Jain <anand.jain@oracle.com>
Reviewed-by: NDavid Sterba <dsterba@suse.com>
Signed-off-by: NDavid Sterba <dsterba@suse.com>