android_keymaster.cpp: Fix compiler warning am: 536357d615 am: 475bdfb87a

Original change: https://android-review.googlesource.com/c/platform/system/keymaster/+/3097437

Change-Id: If6272af955dd03540a69953a85119147a2b5711d
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>