vocore: do not look for factory image (there is none)

targets/ramips-rt305x/profiles.mk

@@ -2,4 +2,5 @@
 
 # VoCore
 $(eval $(call GluonProfile,VOCORE))
+$(eval $(call GluonProfileFactorySuffix,VOCORE,))
 $(eval $(call GluonModel,VOCORE,vocore-squashfs,vocore))