def-tool: Remove a dead argument (cont)

This commit removes a dead argument.  This fixes a regression caused
by a related CL earlier.

Test: ./vndk_definition_tool.py deps-insight \
      --system ${ANDROID_PRODUCT_OUT}/system \
      --vendor ${ANDROID_PRODUCT_OUT}/vendor \
      --product ${ANDROID_PRODUCT_OUT}/product
Change-Id: I70b7132f8c0679bd1cd934bae1066d1f127304f8
1 file changed