Make keymaster optional. am: cc68516bd2 am: d82de97ccf am: e7d8a2a19a am: e4c611ca7a am: aad8fc7940

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1693845

Change-Id: I52c7a2fae18de32abaab64ec7ed2877210da4989