Revert "Prebuilt chromium: Run a check for target device directory"

This reverts commit 5c40db63fe430ce8f21c200c3f1ee295640cfd81.
Revert "build: Add chromium prebuilt support to envsetup.sh && The core Makefile"

This reverts commit d0eab290c650665cc6a501b8cab1e53bd415b975.