Export headers using cc_library_headers am: 393ff671f0 am: 80ca19568b

Original change: https://android-review.googlesource.com/c/platform/external/arm-trusted-firmware/+/2604251

Change-Id: Iac0da023f528176b7272cac93aab13100618daf2
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>