dscpPolicy.c - cache result-less lookups as well

It is most definitely worthwhile to cache negative lookups as well!

Test: TreeHugger, atest DscpPolicyTest
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: Iab1a57a2611a891642fef0c5897918c16e0ca540
4 files changed