KmemTrigger: Don't add FD watches for disabled CPUs
KmemTrigger: Don't add FD watches for disabled CPUs

Bug: 178929757
Test: Boot; Check traced_probes cpu usage in top
Change-Id: I9da3838686319b19f0936253af5bfaac6a2df63c

google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto,google/perfetto