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

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

Change-Id: I5fec86c1cd4ef16e7e390b61c4704d5be3fbbed5
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>