Use accessor for EVP_PKEY types am: 39b1ba3702

Original change: https://android-review.googlesource.com/c/platform/system/keymaster/+/2148656

Change-Id: Ie02e7489cf49d7fda19f76bc85fbcebcc8c1dead
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>