chunker: Remove unused constant
chunker: Remove unused constant

stuertz/restic,ar-jan/restic,klauspost/restic,bchapuis/restic,arithmetric/restic,ar-jan/restic,fawick/restic,restic/restic,kurin/restic,byo/restic,byo/restic,episource/restic,fawick/restic,intfrr/restic,pombredanne/restic,howeyc/restic,kurin/restic,restic/restic,jayme-github/restic,jayme-github/restic,stuertz/restic,middelink/restic,ckemper67/restic,middelink/restic,mappu/restic