Make keymaster optional. am: cc68516bd2 am: d82de97ccf am: e7d8a2a19a am: e4c611ca7a am: aad8fc7940 am: e35115bf1a

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

Change-Id: I8cbe9cd8b952b599bdbd167e548a05143752a4f9