notice_files: Disable NOTICE files for FAKE modules.

Currently the build system will automatically attribute a NOTICE
file with the target of $(BUILD_PHONY_PACKAGE). This shouldn't
be the case.

Disable notice file inclusion for fake targets so that the
/fake_packages/blah_blah-timestamp paths don't show up in
NOTICE.xml.gz.

Bug: 77910458
Test: NOTICE files are not attributed to fake targets.
Change-Id: Ia942cac41b750efbd5a23d896d85ac0820ee8b4e