Remove openwrt modules from genrule denylist.

With the other change in this topic,
`OpenwrtControlServerProto_h` and
`OpenwrtControlServerProto_cc` both successfully build with sandboxing
on.

Test: build/soong/tests/genrule_sandbox_test.py --show-diff OpenwrtControlServerProto_h OpenwrtControlServerProto_cc
Test: GENRULE_SANDBOXING=true m OpenwrtControlServerProto_h OpenwrtControlServerProto_cc
Test: GENRULE_SANDBOXING=true m droid
Change-Id: Id56824ed935e1d16d2333e5a1aeac248cdfcaeb6