Fix incorrect string formatting in WifiChaosTest

Concatenating str with object using '+' causes Exception. Use % format instead.

Bug: 138391184
Test: test in lab
Change-Id: I89daae077cb0cfc23a8d871ee13d35f2ecfc3e6b
1 file changed
tree: 67adf538bf92eab054ad66623917b20c54528397
  1. acts/
  2. tools/
  3. wts-acts/
  4. Android.mk
  5. OWNERS
  6. PREUPLOAD.cfg