smptest: Don't wait 15 seconds for every inactive cpu am: 8c18b06333

Original change: https://android-review.googlesource.com/c/trusty/lk/trusty/+/3503833

Change-Id: If8f3308ec735a54af426a3acbaf93988a2f35471
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>