Use accessors instead of reaching into the RSA struct am: eedfb29cdb am: 676444f63d

Original change: https://android-review.googlesource.com/c/platform/external/vboot_reference/+/2569310

Change-Id: I6d84d25db34b32f8fe4d1e1c6eb8b13ffd2caff6
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>