segbits_hclk_ioi: fix missing ONLY_DIFF_IN_USE

fuzzers/030-iob18/Makefile

@@ -30,6 +30,9 @@ build/segbits_riob18.db: build/segbits_riob18.rdb process_rdb.py bits.dbf
 
 build/segbits_hclk_ioi.rdb: $(SPECIMENS_OK)
 	${XRAY_SEGMATCH} -c 10 -o build/segbits_hclk_ioi.rdb $$(find -name segdata_hclk_ioi.txt)
+# since only LVDS is an ONLY_DIFF iostandard on the high performance banks, LVDS_IN_USE and ONLY_DIFF_IN_USE
+# are synonymous. To prevent dbfixup removing both, because they have identical bits, we need to remove one of them
+	sed -i '/LVDS_IN_USE/d' $@
 
 build/segbits_hclk_ioi.db: build/segbits_hclk_ioi.rdb
 	${XRAY_DBFIXUP} --db-root build --zero-db hclk_bits.dbf --seg-fn-in build/segbits_hclk_ioi.rdb --seg-fn-out $@