dscpPolicy: assume cache lookup always succeeds (though it might miss)

By construction it cannot actually fail, since
  per_cpu_array[cookie % nr_entries_per_cpu]
is always a valid array item...

This allows us to do direct per-cpu write into the cache
instead of going via bpf map update helper function

Test: TreeHugger, atest CtsNetTestCases:android.net.cts.DscpPolicyTest^C
Signed-off-by: Maciej Żenczykowski <maze@google.com>
Change-Id: I8a70ae341b21202db88877856522288149a54f31
1 file changed