Remove ndk_platform backend. Use the ndk backend. am: e11f34b4fb am: 090df9b4f4 am: d0d09e8613

Original change: https://android-review.googlesource.com/c/platform/system/keymaster/+/1779386

Change-Id: I9e08f2951a4606bdbee1413faa8c2fdf1aed1d2a