Clean up keymint ProtectedData documentation am: 1d389acec8

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2075940

Change-Id: I1b62e15a829b1baa3c53b1fdc8533f9e82ed266b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>