Add custom images in fastboot-info

Test: m fastboot_info; m && fastboot flashall
Change-Id: I9a828d35992d684dfaacffd04006d420b7088736
diff --git a/core/Makefile b/core/Makefile
index 94fc88e..50aa11d 100644
--- a/core/Makefile
+++ b/core/Makefile
@@ -5711,6 +5711,10 @@
 	  echo "flash vbmeta_$(partition)" >> $@;)
 endif
 endif # BOARD_AVB_ENABLE
+ifneq (,$(strip $(BOARD_CUSTOMIMAGES_PARTITION_LIST)))
+	$(hide) $(foreach partition,$(BOARD_CUSTOMIMAGES_PARTITION_LIST), \
+	  echo "flash $(partition)" >> $@;)
+endif
 	$(hide) echo "reboot fastboot" >> $@
 	$(hide) echo "update-super" >> $@
 	$(hide) $(foreach partition,$(BOARD_SUPER_PARTITION_PARTITION_LIST), \