vndk-def: Raise unknown vdex version exception

This commit raises a ValueError if the vdex version is unknown.

Test: vndk_definition_tool.py check-dep --check-apk \
    --system ${ANDROID_PRODUCT_OUT}/system \
    --vendor ${ANDROID_PRODUCT_OUT}/vendor \
    --tag-file dataset/eligible-list-${VER}.csv

Change-Id: I95e92c08aa26433e575db482de75f1671bd1f017